Jennifer Lopez says 'PTSD' from failed 2003 Ben Affleck wedding led them to elope

Jennifer Lopez says she and Ben Affleck eloped in Las Vegas in July — prior to their splashy wedding in Savannah the next month — because she had "a little PTSD" as a result of calling off their dream wedding 20 years earlier.

The Shotgun Wedding actress, 53, talked about becoming Jennifer Affleck on Wednesday's Jimmy Kimmel Live. She said "stress" was behind their decision to elope at the last minute, and revealed that Affleck planned the Sin City affair in just a few hours.

"We were planning to get married in August in Savannah — the family [was] going to be there, everyone [was] going to be there," Lopez began, "and it was so stressful."

The "Let’s Get Loud" singer explained, "Twenty years ago we were supposed to get married … and it kind of all fell apart back then. This time, we still — I absolutely did — had a little PTSD. 'Is this really happening?'"

While they were "so happy" and "of course it was happening," she admitted, "I just felt like the wedding was so stressful. One day," after a wedding planning meeting in which an unnamed person told them they should marry abroad and not at their Georgia home, Lopez was feeling downcast and Affleck stepped in.

"Ben just said, 'F*** it. Let's just go to Vegas and get married tonight,'" she recalled him saying.

Lopez had a rehearsal that day, so she didn't think it could work. He told her to go about her day — and he'd handle everything.

"'When you get back here, I'll going to have everything set up,'" she recalled him saying of their A Little White Wedding Chapel affair. "'Let's go. We're doing it tonight.' And we did. It was amazing. It was the best night of my life."

Lopez explained that Affleck’s three kids with Jennifer Garner were at camp, but her two children with Marc Anthony were with them as "our witnesses." She talked about going to the county clerk's office just before midnight to get their wedding license with other couples, who were in shock to see the celebs getting married, too.

She also revealed they declined the option of having an Elvis impersonator marry them, saying, "Just whoever is there who can legally marry us. That's who we'll take."

Lopez said she wrote a song about their wedding called "Midnight Trip to Vegas" for her upcoming album, This Is Me... Now, and the pink Cadillac they posed in is featured. She said the whole album, a bookend to her 2002's This Is Me... Then, was inspired by the "miracle" of them getting back together, which she says is “something neither one of us ever thought would happen." (In November, Lopez talked about their 2003 breakup, saying, she "honestly felt like I was going to die" because she was so heartbroken. "It sent me on a spiral for the next 18 years where I just couldn't get it right … But now, 20 years later, it does have a happy ending.")

Lopez also spoke about having "the whole family" attend their bigger Savannah wedding a month after they eloped. (She didn't mention it but Ben's brother, Casey Affleck, didn't attend.) The wedding was held at Ben's home there — where they were originally to tie the knot in 2003 but called things off.

In the conversation with Kimmel, she also dished on getting a new engagement ring, an emerald, because she no longer had the infamous $2.5 million pink diamond Affleck gave her when he first proposed in 2002. She also said she's learned to embrace their couple nickname "Bennifer," saying back when they first dated, it was used to mock them.

Wednesday night was the premiere of Shotgun Wedding — which sees Lopez and Josh Duhamel's characters attempt to say, "I do." While Lopez walked the Hollywood event’s red carpet solo — making heads turn in a see-through dress with gold crystals — Affleck attended as her plus-one, later planting a kiss on her cheek at the afterparty for the movie, which premieres Jan. 27 on Amazon Prime Video.

Lopez recently talked about the "emotional transition" they've gone through blending their families after the wedding, and she spoke about that more on the red carpet.

"It’s going really, really well," she told Extra."We have five beautiful, beautiful children, blessings… We dropped one of them off at school today and we were just kind of thinking about what our lives have become and just feeling so blessed and grateful for where we wound up in our lives."