Housemate playing mind games?

He slaps my butt all the time and pushes me around. He always tries to make me angry and then giggles over it. Like ill be sitting on the couch and hell lay on it and stick his feet in my face and tries to put his toes in my mouth or ear. He acts so immature sometimes, but other times he protective and seriouse. Like the other day he got himself covered in burn marks cuz' I was an idiot and put vegetable oil on a heated pan and it spurted everywhere and he grabbed me and went in front of me so I didn't get anything, though I got it on my arm, he got it all over his back and legs, just everywhere..I felt horrible. A while back he freaked out cuz' he didn't want me to go to prom with my bf because he believed I was gonna loose my virginity. Which I wouldn't do, I'm not a slutty skank lol. Tonight he realy made me want to smack him, I was putting the cookies we made earlier into baggies and he came up behind me and put his hands on my shoulders and slowly slide them down to my hips and I pushed back and I knew my face was scarlet red, and he laughed at me! We're the same age and have been living together since we were 15 for two years and our relationship has gotten so complicated and confusing, I don't what to makeof it. It has my friends (including guys) thinking we're in the sack and some people in the our family are questioning us. I deny everything cuz' I have a bf, but idk about him, he has a gf though..I think he acts this way because his gf and me are complete opposites, she's shy and innocent and I'm loud and not afriad to say what's on my mind. Any advice or help, please no immature answers!