Updated

Aaron Carter has broken off his engagement to his older brother's ex-girlfriend.

The 18-year-old pop singer called off his engagement to 22-year-old actress Kari Ann Peniche just a week after he proposed onstage in Las Vegas, Us Weekly reported Sunday on its Web site.

Peniche is an ex-girlfriend of Carter's 26-year-old brother, Backstreet Boys singer Nick Carter. She's also a former Miss Teen USA and former Playboy Playmate.

"I got caught up in the moment and proposed," the younger Carter told the magazine. "I then realized it was a hasty thing to do and I am not ready for marriage quite yet."

Attempts by The Associated Press to reach a representative for Carter were not immediately successful Monday.

Both brothers will appear in the reality series "House of Carters," which debuts Oct. 2 on the E! network.