Mocking Bird

Since I've moved in with my boyfriend, his mother, and grandmother. I never had to deal with the anything you say gets repeated to mother dearest. Every time even it's a repeat of what I told her, he manages to repeat and make it sound like I'm bitching. Or if she did something that make me a little irritated, I mention it he blows it out of portion and again comes back as bitching. He starts fights with her over small little things that just irritate me, nothing else. Yet I can't be surprised because he also tells her about what we do in bed, yet I'm getting to the point I'm not telling him anything just getting up set. What should I do?