New York ? You might think a play about madness would be the last thing Anne Heche would want to do these days.

You’d think that delving into the torturous relationship between an insane father and his on-the-edge daughter wouldn’t appeal to Heche after her much-publicized breakdown two summers ago.

You’d think wrong.

Last week, Heche replaced Jennifer Jason Leigh in the Broadway production of “Proof,” the Tony Award-winning play by David Auburn that promises to blur the line between the actress and her newest role.

“We’ve definitely walked into metaphor land for Anne’s life,” says Heche after a recent rehearsal in Times Square. “There are many, many parallels in here.”

Heche plays Catherine, the daughter of a math genius whose once-sharp mind deteriorates. It is Catherine’s fear that just as she shares her father’s flair for numbers, she also will inherit his madness.

That fear Heche knows all too well: In her autobiography published last year, she revealed that she had been molested as a child by her father, a secretly gay strict Baptist who died of AIDS in 1984.

“I know that I have a close connection, certainly, to the fear of being my father that Catherine has. Even though my father was never diagnosed with schizophrenia, there was certainly a thought that he might be. And even though I was never diagnosed, there was a thought that I might be.

“The funny thing is, there’s an understanding of madness in this play that comes from the father after he’s dead. I think what’s unique about my personal story is that I’ve understood my madness while I’m alive,” she says.

‘I was unreachable’

As she talks, Heche is putting the finishing touches on a homemade Father’s Day card for her husband, cameraman Coleman Laffoon. The couple produced little Homer Heche Laffoon in March.

Heche, 33, gleefully folds pieces of construction paper and scatters store-bought stickers of stars and circles around her crude drawing of a necktie.

“I think he’ll love it,” she says, inspecting her work.

It’s the very picture of family bliss, miles from the turmoil of her childhood and unhappiness following the end of her three-year relationship with comic Ellen DeGeneres.

“To me, the difference between sanity and insanity is that insanity means that you can’t connect the dots of your life. You are out in an unreachable place,” Heche says.

“At moments in my life, I was unreachable. I figured it out, put it all together and connected all the dots by the time I was 33 and understood it. Now, I’m on the other side of it.”

These have been a remarkable last few years for Heche. There was the breakup with DeGeneres, a mental meltdown, her surprise marriage, the tell-all book and a gurgling baby.

DeGeneres and Heche announced on Aug. 19, 2000, that they were splitting up. Just hours later, police were called after Heche wandered into a rural home near Fresno, Calif., appearing shaken and making strange comments to the homeowners.

She later explained in her autobiography, “Call Me Crazy,” that she had suffered a breakdown and that sexual abuse by her father drove her insane, leading her to believe she had a split personality named Celestia.

“I look at my life and I joke about it as being pre- and post-Fresno,” Heche says. “It’s like when I truly say that I understood. That was THE moment of my life. Then everything fell in place.”

‘There’s no turning back’

After taking a year off from acting, Heche says she has recovered from her mental illness and is itching to perform again. The Heche theatergoers will see, she says, will be someone they may not recognize.

“I was hiding when I was acting before and I was good at the hiding,” says the star of “Six Days, Seven Nights,” “Volcano” and Gus Van Sant’s remake of “Psycho.”

“I would become the character completely and fully because I didn’t want Anne to be seen. But now I have nothing to hide and I can walk on stage with myself on board,” she says. “I’m all stars and glitter right now in my head. So I really need characters to leap into.”

With “Proof,” the actress is returning to New York, where her career began aboard the soap opera “Another World” in the ironic double role of twins one good, one evil. So convincing was her portrayal that she won an Emmy.

She has titled her latest adventure, “Anne on Broadway.”

“There’s no turning back,” she says. “Certainly, there’s no going to my trailer if it doesn’t work, there’s no, ‘Can we have another take?”‘

Heche follows in the footsteps of Leigh and Mary-Louise Parker, who originated the role Off-Broadway and who won a best actress Tony for her Broadway performance. Gwyneth Paltrow is playing the part in London and is slated to star in the movie version, to be released by Miramax Films.

“Every day, there’s a new discovery and a new fear,” Heche says. “Today’s fear was, ‘Oh, my god. Even if I can play this, how am I going to do it for 3 1/2 months?”‘

The audience may find it difficult to separate Heche from her post-Fresno revelations, a fact of which Heche is well aware. “Leave your preconditions at the door,” she advises.

“Because I’ve gone off the path of actress into some places that people don’t like me to go, will they be able to come back to the fact that I’m an actress? I don’t know. …

“Hopefully, they will understand and be able to see how far I’ve come … that my life has led me to the richness and fullness of being able to do this show.”

As for the turmoil in her past, Heche says it’s just that in the past.

“It’s a part of me, don’t mistake that,” she says. “I don’t deny it. I just embraced it. And now the color has changed from black to clear.”