facebook privacy problem?

[REHAN]

umm.. my roommate/friend is a total asshole. i dont know why but facebook shows him everything i do. if i post something on a page that he hasn't even liked. if i like some photo. if i add someone. and he always keeps trying to make fun of everything. i used to just ignore him since now. but now i finally asked the girl i liked at college her facebook id and i want to add her but i'm annoyed by the thought of him doing something again. e.g., a few days back i added a female friend at 2 am and he got that on his newsfeed and made a meme of it calling me a pervert :/ i know its not funny but its totally different now. i dont want him to create a bad impression of me on that girl. i also cannot block him as he's my roommate and friend. so please tell me how to set privacy settings so that he won't be able to get much updates on me without blocking him.