Do you think i should be friends with this guy?

I have a friend (well no really my friend) but he has been my friend sence 3rd grade nd now im in 8th. me and him were really really good friends... we could teel eachother anything. but ever sence he got a girlfriend hes been acing different. everytime i talk to him or his girlfriend he either hits me or kicks me. one time him and his girlfriend were hugging in the hall and i went uo to then and said "awww" then he punched me in the stumach and i had a bruse there for a week. what do you think i should do about it? should i stay friends with him? or just stop talking to him? please help me