Jenny Boylan describes that turning point at the train tracks in her new book, "She's Not There," the wrenching story of her 40-year struggle to be someone she knew she was not.
"There was really no choice for me, except to become the person I'd always been on the inside," says Boylan.
Jenny Boylan was born James Boylan, and he grew up in a small town outside of Philadelphia. He told Correspondent Susan Spencer that he spent much of his time and day dreaming about being a girl.
"There was a day when my mother was ironing, and she was showing me my father's shirts that she was ironing. And she said, 'Someday you'll wear shirts like this.' And I thought, 'Well, why would I wear shirts like his?'"
Childhood, he says, was painful. "You cannot imagine the isolation and the sadness that you carry around as a child knowing that you need this impossible thing."
So, when alone, Boylan played a different role and put on girl's clothes.
"What it would be, in a sense, was a moment of not having to think about it. Now, I feel normal," says Boylan, who told no one about what he did. "I kept it secret because I didn't want it to be true."
Looking at photos, Boylan said he wanted to be someone who was different: "I didn't want to be someone who would be seen as an outsider … I had thought my whole life that if I were loved deeply enough by someone else, I would be content to stay a boy. That it wouldn't be the best life, but it would be the second best life."
At 29, Boylan fell in love with a woman we'll call "Grace." "I believe it's kind of a nice period in my life," recalls Boylan. "In fact, for a while, that sense of needing to be female disappeared, and I felt like I was cured."
He says he took drastic action to change his life: "I had blouses and skirts and makeup, and I got a garbage bag, and I remember standing there thinking, after all these years, finally, we will leave this here forever."
The couple married in 1988, moved to Maine and had two boys. Boylan taught English at Colby College, wrote novels and played in a local rock band. On the surface, life was good, but gradually, the old feelings were coming back.
Even though my life has been transformed by love, I still feel like a woman inside.
In the winter of 2000, Boylan realized he could not take one more step as a man, and had to tell his wife the truth.
"She wept and I wept, and it was clear to her that she didn't want to lose me. And she didn't want to lose our lives together," says Boylan. "But in many ways she had. What she has lost, what we have lost, is a marriage."
"There's absolutely no way to escape this. It is on that person's mind all the time," says therapist Kathleen Farrell, who has been treating transsexuals for almost 20 years.
"A transsexual is a person whose brain sex is different from their body gender. It is something that a person is born with, and there is no other choice for them."
The American Psychiatric Association has recognized this condition, calling it gender identity disorder.
But Boylan defines it by explaining what it's not: "If people see someone like me, they think, well, that person must be gay. Or they think, well, that person's cross-dressing. Or people will think this is a lifestyle -- and none of those things are true."
Experts aren't sure what causes it, but one study did find telltale structural differences in the brains of transsexuals -- especially in an area deep inside the brain called the hypothalamus, which is associated with gender and sex.
It turns out male transsexuals, men who see themselves as women, have brains that look more like women's than like other men's.
With the help of doctors, Boylan started the slow transition into Jenny -- going to therapy, dressing as a woman, and taking female hormones.
"The first thing that happened is something called fat migration. All that fat goes to your bust and to your hips. My hair got fluffier. The hair on my arms melted away," says Boylan. "Above all, there was a difference in the way that I felt, the way that I occupied my body."
Boylan was becoming the girl she believed she was born to be. But now, she had to explain that to her two sons, then ages 4 and 6.
"I said, 'I have a medical condition that makes me look like a boy on the outside, even though I feel like a girl on the inside. And I'm gonna be taking medicine that's gonna make me more and more like a girl. I know that might make you sad,'" recalls Boylan. "And he just interrupted me, and said, 'Well, why would it make me sad? You said you'd still be you.'"
Boylan insists the children are fine – they call her "Maddy," a cross between mommy and daddy. The kids, however, were off limits for interviews, and although Grace didn't mind being photographed, she declined to be interviewed on camera.
"She [Grace] doubts that her story could be presented in a way that people would not pity her. And I think she does not want to be pitied," says Boylan.
They are no longer husband and wife, but they are close -- and Grace has decided to stay with Boylan, at least for now, for the sake of the family.
"She's absolutely a saint. There's no question. And maybe I should leave it at that," says Boylan.
As Boylan started showing signs of womanhood, she knew she had to tell her friends – friends she had made as James.
John Clark, a pal since the seventh grade, initially struggled with the news: "We all felt very sad for Grace. How could you do this? How could you go ahead and get married and have two children and never tell her? That your whole life -- you thought you were a woman?"
But Clark now accepts that Boylan had no choice but to become a woman. "There's no way any rational person, any smart person, would put yourself through what she's had to do to risk everything," he says.
Finally, at 42, Boylan took the last monumental step – surgery, which for her was a completely natural step. "I was ecstatic. Imagine, you're a woman and you have a penis. I mean, talk about embarrassing. Talk about mortifying," says Boylan. "So for me to be myself after all of this time, it was a miracle."
So how did the surgery go? "Without going into a lot of details, the surgery is very good," says Boylan. "The plumbing works and so is the electricity."
Her colleagues at Colby have been totally accepting – even promoting her – but she says students react to her differently now: "It used to be I would go in, and I would start giving my lecture. And people would write it all down, because I was an authority figure. And now, if I go in, and give that same lecture, often people won't open their books."
With her book, "She's Not There: A Life in Two Genders" now out, Boylan is eager to share her story.
"It's a good thing I wrote this book, because people can see, and also, that I'm not a crazy person," says Boylan.
And she's not even a different person, although she may now be the right person – and one who yearns to be accepted.
"When people see me, they don't see some honking transsexual. They see a good parent," says Boylan. "And when you see our family, it doesn't seem like an unusual thing. You see four people who love each other."