Advice?
Leave her. She's already left you. She wouldn't "lead him on" and admit to it. Unless she's not that smart. If she IS leading him on, why wouldn't she do it to you? How do you know she isn't?
And, likely she was sleeping with this guy within two weeks of you splitting up. That's the reality. He was a rebound for her, and he was playing up the nice guy angle, and she fell for it.
More advice?
Don't ask for love advice on a car forum.
