My mom's boyfriend has the whole "Every body's Being So Mean To Me" mentality. How do I deal?

My mom's boyfriend is getting on my last nerves. If I say I didn't give him a dirty look when he said I did, even though I didn't, he has this whole mentality that I call the "Vienna From THE BACHELOR" mentality that annoys the heck out of my mom and I. He does the whole "Everyones Being SOOO MEAN TO ME" routine where he whines like a little cheerleader and makes false allegations against me. Sometimes, my mom believes him just to avoid drama when she's right there. When he does it, it makes me want to rip my hair out. I think, "He's doing this to annoy me. Hold it together and don't even dare to give him a reaction", but it occasionally dosn't work when he acts really mean. I can't tell him that it gets annoying after the last few times because he'll keep doing it. Case in point? How do I deal?