Drew Barrymore's Last-Minute Wedding Drama

Talk about pregnant pause! Shortly before mom-to-be Drew Barrymore's June 2 wedding to art dealer Will Kopelman, she had a heart-to-heart conversation with ex-boyfriend Justin Long — and considered canceling the nuptials after he warned the free-spirited actress against tying the knot a third time, a source tells Star.

OK! NEWS: DREW BARRYMORE GETS MARRIED!

"She got a call from Justin a couple of weeks ago, and it kind of shook her up. She started questioning everything," says the source. "He wasn't calling to beg for another chance; he just wanted to gently tell her he thought she was making a mistake. Her track record with marriages hasn't been very good, and Justin wanted to voice his opinion that she should think long and hard before committing herself again."

Though Drew, 37, and actor Justin, 34 — who costarred in the 2010 flick Going The Distance — officially broke up in July 2008 after nearly a year as a couple, they continued to spend quality time together, and were even spotted snuggling up in a NYC bar shortly before Drew and Will, 34, began dating in early 2011.

"Justin feels like he knows everything there is to know about Drew," the source tells Star. "He knows how heart-wrenching her two divorces were. He doesn't want to see her get embarrassed again."

OK! NEWS: DREW BARRYMORE PREPARES TO WALK DOWN THE AISLE WITH WILL KOPELMAN

As Drew struggled with her thoughts after talking with Justin, the source tells Star, her best pal, Cameron Diaz, stepped in to right the ship.

"She was a huge help," says the source. "She talked sense into Drew and got her to realize that running away from marriage because of a fear of failure is a self-destructive thing to do."