His mom is visiting

Okay ladies. A little help here. The SO mom is coming to visit and stay with us for a week. There is tension between me and his mother for one main reason. When he and I started dating she called a friend of hers who just happens to be my mothers neighbor. She asked this lady about me. The neighbor proceeds to tell her about my wild teenage years. Yes I was a little wild as a teen but who wasn't. So his mother calls him as tells him to leave me because I was "easy". According to my SO he told his mother everyone has a past and he doesn't care about mine. But ever since then whenever she calls she'll  bluntly ask me if I've been faithful or if he's unhappy with me. WTF!!!!! I've told him about it and he says she's just looking out for him and she means no harm. How am I supposed to put up with her for a week in my home??? HELP!!