'The Bachelorette': Xavier Stuns Charity as He Admits His Past Infidelity Ahead of Fantasy Suites (Exclusive)

The child and family therapist was cheated on in her past relationship.

Charity Lawson is learning some unwelcome news. In an exclusive sneak peek clip of Monday's episode of The Bachelorette, Xavier comes clean to Charity as he reveals that he cheated on his past girlfriend.

The moment comes during the nighttime portion of their date in Fiji, before they are given the option to forego their individual rooms in favor of the Fantasy Suite.

Things start on a positive note, as Xavier tells Charity, "Today was incredible. To be in Fiji, on a private island with you is all a man could ask for, for real."

In a confessional, though, Xavier admits that he has something big on his mind. "With an engagement right around the corner, it's important to share with her who I am completely," he tells the cameras.

Given that, Xavier opens up to Charity, telling her, "We started to dive deep and I know an aspect that was very serious for me -- that is very serious for me -- is, in the past with my ex, I was unfaithful."

Charity's jaw drops in reaction to the news, especially as she's been vocal about how she was cheated on in a past relationship.

"I thought you deserved to know," Xavier tells the stunned Bachelorette.

It's no surprise that the drama is ramping up as only three suitors -- Xavier, Joey and Dotun -- remain. When ET spoke to Charity in June, she teased that the drama would only increase from Fantasy Suites week on.

"It's definitely gonna pick up some heat around Fantasy Suite week," she said. "That whole week, and then thereon after... Just expect it all, truly."

And while she wouldn't reveal if she's engaged now that the show's wrapped filming, she did confess, "I'm happy with how the season turns out... I'm very proud of myself."

Watch Charity Lawson's journey for love on season 20 of The Bachelorette, which airs Mondays on ABC. Stay up to date on all the drama by following along with ET's coverage of the series.