Reporter: The morning she is scheduled to die, Jennifer Schwab is actually on her way to work. Up before dawn, out on a dark and lonely road. Something frightening coming from behind. A car, following... See More
Reporter: The morning she is scheduled to die, Jennifer Schwab is actually on her way to work. Up before dawn, out on a dark and lonely road. Something frightening coming from behind. A car, following her. And tonight for the first time she's coming forward to tell her story. Tell me about the morning you left. Were you going to work? I was, yes. Every time I left my house I would check outside to see if there were any unfamiliar vehicles. Now, one morning I looked across the street and there was a black car that was across the street. They followed me. So you're wondering who it is behind you? Yes. I was on the phone with my mother, and I said to her, "Mom, let me call you back, I'm getting pulled over." I got pulled over. So, the lights go on. The lights go on. And you're thinking, "I ran a red light." I'm thinking I'm speeding, I'm being caught on the phone, I didn't know what. They're behind you. They start walking up to the car. Yes. And you roll down the window. Just a little bit. How do you tell someone that there's been a threat against your life? We wanted to reassure her that we were there to protect her. The ATF officer places his badge against my window and says to me, "Are you Jennifer?" And I said, "Yes." And he says to me, "Jennifer, there's been a hit for you life." I remember clearly saying it, flat-out told her there'd been a threat against your life and you know we were there to protect you. And immediately I said to him, "Nicole faccenda." I think that stunned the two of us, because, you know, I didn't know that she knew of such a threat against her. But obviously, it was something that immediately came to Jennifer's mind that Nicole was someone that was looking to harm her. So you knew right away. I knew right away. I even had said to my, my people I work with, my friends, my family, "If anything happens to me, it's Nicole." So I knew. Reporter: She says she had always been wary of Nicole, and knew she could be trouble. But could you ever have imagined this? I thought maybe it would just be a flat tire, or you know, a broken window at the house. I never thought that she would go to the extent as she did, as to try to find somebody to murder me and my family. Reporter: Jennifer says Nicole never really had a chance with the man in the middle, Howie. Howie's double life, the two-timing, the cheating? All in Nicole's head, according to Jennifer, who says Howie was always hers. What drives someone to do that? Jealousy and anger. She wanted him. She wanted him. She wanted him from the time that I met him. But what you're telling me is that she never really had him. That's correct. Reporter: But don't forget Howie and Nicole have a child together, a son, 11 years old. And at one point, when Howie and Jennifer broke up, Howie moved back in with Nicole. There was a lot of pressure in our relationship. And Nicole made it easy for him, manipulated him by saying that she would help him financially and, you know, that she could do things for him that I could not do. And that hurts. That hurts to know that because of money and greed, you know, he left and went to live downstairs in her basement. Reporter: And for those of you thinking Howie is a two-timer, Jennifer says he's not. The double life that people said he lived is not the double life he lived. But she wanted you wiped off the Earth. Yes. And when you hear it from her own mouth -- If something happens to one of the kids, I'm sorry -- How did you react? Hurt. Angry. I can't fathom how somebody, a mother, Nicole being a mother herself, would want to do to myself, my family, and my children. Reporter: Jennifer never saw the surveillance tape of that murder plot unfolding in that supermarket parking lot until she saw those tapes played right here on "20/20." I will be happiest when she's dead and buried and six feet under. She said she'll be happiest when this woman is buried and six feet under. Mm-hmm. It makes you so angry to hear those words. I led my life, I raised my kids. I didn't do anything to deserve this at all. Does it sound like something out of a -- A, quote, "Lifetime movie?" Absolutely. It does. Nicole never got the best of me. I'm too strong for that. And that's what I really think made her go to this extent of trying to murder me. Reporter: The agents take Jennifer into protective custody, her first instinct to check on her two young sons. I wanted to make sure that my family was safe. Reporter: But she's not allowed, because now it is the agents whonnant jeifer to disappear. Part of their own plan, taking her phone, cutting her off from the rest of the world. You couldn't make any phone calls. I could not make any phone calls, no. Because they told you this plot is unraveling right now. Correct. Yes. And we need you. Yes. Reporter: Because what those agents are going to need is for Jennifer to play dead. We needed to kind of close her off and really simulate what it was that we were trying to effect. There's always a threat, which is why we still had to bring her into our protective custody and keep her pretty much dark from her family and her friends that day, so that we can go ahead with the rest of the story, that the murder had been committed.
This transcript has been automatically generated and may not be 100% accurate.