Jon Gosselin's first interview together with girlfriend Hailey Glassman, only on ET: Could it be their last? Will they split up as ET cameras roll?

Last night Hailey broke down in front of our Mary Hart as Jon watched. At the beginning of the interview, Jon did not intend to participate. He sat just five feet away, listening. Then, he finally decides to join Hailey -- and that's when the conversation turns to estranged wife Kate Gosselin.

"I tell him all the time that he should be friends [with Kate]," says Hailey. "I tell him for his children, you need to be friends. I don't think you should be split up on Thanksgiving. I don't think you should share time on birthdays."

"I want to own up to my mistakes," says Jon. "I want to ask for a second chance. I want to apologize to Kate, in person. I just need to start over from ground zero: Be trustworthy, honest, have a good moral compass and do the right thing."

The conversation turns to the future of Jon and Hailey's relationship, and Mary asks, "You're going to end the relationship now, at least for awhile?"

"We're going to take a break and decide," replies Jon. "We'll let Hailey decide on what she wants to do. … My life is so hectic right now I have to concentrate on my own decisions. … Maybe she wants to go get a job. Maybe she wants to date other people. Maybe she wants to experience life? Live on her own and do her own things. I don't know. If I was 22, I would probably want a break too, because it is so much."

"It's hard, because when I do [try to leave], he cries," says Hailey. "As hard as it is for us, he needs to go handle his stuff, be with his family and handle his divorce, and I need to go and be a 22-year-old and get my life back."

At this point in the conversation, Mary says she feels less like an interviewer and more like a couples' counselor.

"I have to let her go in order for her to be happy," says Jon. "If she thinks I've been emotionally abusing her, I cannot live with that guilt."

"Everything's easier said than done," says Hailey. "Even when I'm sitting in this interview and I hear you talk, saying that you're gonna be more honest and loyal, I roll my eyes like the rest of the world. I wanna see it!"

At this point, Jon starts to become emotional. Is the couple literally breaking up right in front of Mary and the ET cameras?

"I don't want to do this on national TV -- this is serious," says Hailey.

"I wanted to discuss this in private, but now it's public," says Jon. "I'm getting frustrated, because it's uncomfortable. This whole thing's uncomfortable. I don't like it. I mean, you're telling me out there that you love me and you want to be with me, and then you..."

"I do love you, and you tell me you love me -- we would love each other and we want to be with each other, but it's not healthy!" says Hailey.

"I'm not talking anymore," says Jon, shutting down.

With the atmosphere growing ever more intense, Hailey brings up Jon's kids, and suddenly he's had enough.

"I constantly would tell him, 'Don't you wanna be a more honest person, for your children? Not for me, not to get validated by the public, but for your children?' Don't you want them to look up to you and say, 'My daddy's honest'?"

"I'm not talking about this," says Jon -- and with that, he storms out of the interview and is gone.

But after the plug gets pulled, is this truly the end of the interview?

Watch ET Wednesday night for the explosive conclusion!