Sexual Assault by a friend

So I'm studying to be an engineer which means most of the people in my classes are male. My friends are a group of 7 guys and one girl who is dating one of the guys. The single guys in the group tend to hit on me usually just playfully, but one of them over the spring semester got increasingly handsy. One time I slept over his dorm because it was too late to walk the 2 miles back to my dorm and it was snowing so he let me stay in his bed. During the night he joined me and while he thought I was sleeping he put his hands on my breast. I immediately moved away and told him that wasn't okay. He said sorry and then when we settled down again he pressed himself into me. I didn't like that so I got up and left. The next day he apologized. He continued to do little things like grabbing my breast while we were talking or smacking my ass while I was walking. He wouldn't listen to my wishes for him not to. He couldn't pay tuition for next year so he knew he wasn't coming back. And when I went to watch tv with him to say goodbye the last day of school because he asked me to he jumped at me and tried to kiss me saying that he knew that I wanted to have sex with him before he left. I was having none of that so I pushed him off but he pushed back and kissed my neck as I screamed for him to get off me. He pulled away and asked why I didnt want to have sex with him. I didn't even respond I just left. Over the summer he continuously asks if we are all going to hang out and the group keeps getting mad that I don't want to go near him. I told the rest of the group already but they continue to talk to him even though he did that and still get mad that I refuse to see him. I feel like they don't believe me and they don't have my back when it comes to this stuff. Should I be upset that my friends are still okay with a guy that attacked me?