"I'm engaged," she tweeted Friday.
"Thanks for all the congratulations everyone, I'm a very happy lady indeed and all the warm wishes are well appreciated!" she said. "We plan to keep our special day very private and we hope everyone can respect that. Thanks for the love, right back atcha!"
Grimes, 23, is a cast member of TV's "90210."
Swim Week Miami Beach 2014 [PHOTOS]