On a recent episode of HBO's hit series "In Treatment," the therapist, played by Gabriel Byrne, complains to his new shrink, Adele, that his old shrink, Gina, used him for a character in her novel. As a shrinkaholic author with a tendency to triangulate, I could relate.

"Aaron misses you and can't live without you," was Dr. W's first line at our first session.

I turned to my handsome, curly haired off-and-on beau of six years, sitting beside me on the couch of Dr. W's office. I was a 35-year old, fast-talking Manhattan journalist, with a raspy smoker's voice and no patience, who'd left Aaron because he couldn't commit. Yet after three months apart, he coerced me to a couples session with his new therapist, Dr. W, "just for closure."

"He's so happy you could make it here today," Dr. W added.

"And who are you, Cyrano de Bergerac?" I asked.

Both men were mid-40s, a decade older than me, yet otherwise they seemed opposites. Aaron was a 6-foot-4-inch, burly, shy, bespectacled Jewish bear in jeans, an untucked shirt and unlaced sneakers. He'd never lived with a woman. Growing up, his suburban folks monitored his television viewing and diet. So he became a nerd who loved pizza and chocolate pretzels, published the anthology Junk Food, and feared emotional insight would ruin his career as a TV comedy writer.

Dr. W was a very slim, dashing, 6-foot-tall, clean-cut, Type-A urbanite WASP in ironed khakis, a button-down blue shirt and tie, an athletic health-food nut who sprinkled stories of skiing and whitewater rafting with his wife and kids into conversations. Pushing Aaron to overcome his marriage phobia, Dr. W took out his calendar and said, "Today's October 6. Can we say you'll propose by Halloween?"

Speed Shrinking, a book by Susan Shapiro"How about November 22?" Aaron asked, the negotiation now between the two men. "The day Kennedy was shot," he added.

"He's just nervous. He does want to marry you," Dr. W assured, basically proposing on Aaron's behalf.

Aaron later told me Dr. W said I was "a woman of substance" and he'd "never do better." On Nov. 22, Aaron showed up with a diamond ring. We invited Dr. W to the wedding; he didn't come.

Five years later, awash in book rejections, I was chain smoking, toking and drinking, my horrible mood and habits wrecking our marriage. This time Aaron gave me the ultimatum: Clean up my act or he'd leave. He said Dr. W was an addiction specialist with graduate degrees in substance abuse, offering to pay for my treatment.

"Commit to see me weekly and do everything I say, and in one year you'll be smoke-free and sell your book," Dr. W promised on our first solo session. How ridiculous. But this was the guy who got me married. So I took the risk. Going through withdrawal I'd never felt so vulnerable. Dr. W calmed me, taught me how to "suffer well," scrawling Haiku-like mandates on the backs of his business cards: "Addicts depend on substances, not people." "Hold Aaron for one hour nightly with no talking," "Make me and Aaron your core pillars."

After nine months, I was smoke-free, sold a memoir and started another -- about the addiction therapy. Dr. W read it chapter by chapter and loved it. I felt hyper and joyous, like my brain was on fire.

Confiding my lack of intimacy with Aaron, Dr. W insisted I reveal all my fantasies to my spouse so we could act them out in bed. At first Aaron balked. "According to the Torah, a Jewish man who doesn't carnally satisfy his wife isn't a good husband," argued our skinny Protestant shrink. (Had they taught this in Hebrew school instead of the Holocaust, I might have kept the Sabbath and learned to cook a brisket.)

Five years after we wed, I fell madly in lust with my husband. Filled with gratitude, I gave Dr. W a Waterman pen and rare Freud first editions. I saw him twice weekly, emailed daily, suggesting we co-author an addiction book. I worried my feelings for him constituted an emotional affair. Yet Aaron liked having a pinch hitter, often mumbling, "Don't know, call Dr. W" or "this pillar's tired."

So I leaned on the other one, causing Dr. W to label me his "most taxing patient." I wondered if "the transference cure," where patients get fixed by sheer devotion to their therapist, described us. My best friend asked if we were sleeping together. Of the many inappropriate aspects of our relationship, that wasn't one. I was sure he'd never touch a patient.

Still, Dr. W was a boundary breaker, always late, switching appointments constantly, making me crazy. His flakiness recalled cads from my past. The more harmonious Aaron and I became, the more I fought with Dr. W. I now had the perfect spouse while paying Dr. W to be the bad boyfriend. He also played the role of real estate adviser, encouraging my idea to buy the apartment next door and combine them. Aaron said we couldn't afford it.

Dr. W, a financial whiz, said we could. Aaron landed a big TV job that (despite his reluctance) wound up covering our dream home.

After Dr. W helped me quit alcohol, dope, gum and bread, I joked the only compulsion left to quit was him. But he quit me by moving away in 2006. I saw him when he came to town monthly, emailing constantly. The pain of his desertion inspired the first novel I was ever able to sell, my obsession with him fueling my creativity. A Jungian friend said, "He's the poison that cures you."

Alas it became more poisonous when a pretty red-headed student from my writing workshop called Dr. W for an appointment. She'd already seen two former shrinks of mine so the connection felt creepy. Knowing good therapists won't treat a patient's friend or colleague without permission, I told them both it made me uncomfortable. She ignored me and quit my workshop, emailing she was unable to hear about Dr. W, "now my shrink too." Then she didn't return my messages. Neither did he. I woke up at three in the morning, screaming from the nightmare that they were eloping together, deserting me. I lost my appetite, dropping 13 pounds in two weeks.

My usually mellow husband told Dr. W, "You're hurting my wife. You screwed up. Fix this!" Dr. W said it was just a misunderstanding, promising he wouldn't treat the redhead. Four months later, as my debut novel about Dr. W launched, he was late for our session, asking me to wait upstairs. Too hot, I stood outside. I saw red braids bouncing out of his office. He'd not only lied, but I couldn't believe he'd colluded with my student to deceive me. I'd never felt so heartbroken.

After 15 years of trusting Dr. W implicitly, Aaron exploded. He cut off all contact with Dr. W, forbidding me to answer his messages and emails. I started sleeping soundly again, waking up safe in Aaron's arms. He'd become my savior and protector. For six months I ignored Dr. W, mourning his loss. My husband, too, was bereft without him.

"I feel like I cut off my arm to prove my love to you," he admitted. My marriage was founded on a triangle. We were divorcing our third wheel.

Then Dr. W emailed me a mea culpa. Aaron said, "He was generous and kind for 14 years. You have to forgive him." I refused to return to his office, the scene of the crime, suggesting the nearby bistro where I'd held my bridal shower. Aaron didn't want to see him but offered to wait outside if I needed him to. I went alone. I wouldn't be married if it wasn't for Dr. W, I thought.

For the first time, he was early. I guessed the bistro owner wondered who this well-dressed man was, and why I wasn't with Aaron. Or was I the one wondering? I played out potential bad endings: Dr. W could be hostile, or refuse to rehash it since the redhead was still his patient. Sinatra's "I've Got You Under My Skin" played.

"I'm sorry I hurt you," he said.

"Traumatized," I corrected. "I've felt more emotions with you than anyone. I loved you, needed you, idolized you, hated you, killed you off, mourned you, and now you're being resurrected."

"How Catholic of us," he said.

"So how are you?" I asked casually, as if my sanity didn't depend on his answer.

He revealed his wife had been very ill, which distracted him. He hadn't treated my student in months. It was a mistake, he said; he'd never see her again. His eyes didn't look menacing, just haunted. If Aaron was seriously sick, I would lose it too.

"I'm so sorry. I didn't know," I said, spooning honey into my tea.

"You're using too much," he commented.

As intimate as we'd been for a decade and a half, I realized we'd never sat in a restaurant together. Part of me had really believed I was his other wife. Thus I'd deserved control over who Dr. W saw, why I couldn't handle him "cheating" on me. Now I saw Dr. W needed the break -- to take care of his actual family. Over the months we were estranged, Aaron became my closest confidant and true partner, taking care of me emotionally, the way Dr. W had.

Dr. W signaled the waiter for the check. An hour had passed, our time up. I let him pay.

I went back to trusting him, though not enough to pay him to shrink me. Still, Dr. W had helped me get clean and sober, triple my income, enhance my marriage. I couldn't give up my lucky charm. Indeed, "You can do anything as long as it works," was one of his mantras. When my agent offered to sell the addiction book project we'd started years earlier, Dr. W was thrilled. Publishing a book on his brilliant addiction theories felt like good karma.

I asked Aaron -- who never wanted to collaborate with me work-wise -- whether he minded if Dr. W and I become co-authors. "Good, you two can pay the mortgage he got us into," he joked. Hugging Aaron, I heard myself say, "You're the best husband."

Susan Shapiro is a Manhattan writing professor and the author of the memoir "Lighting Up" and the recent novels "Overexposed" and "Speed Shrinking."