how to act around people who have hurt you???

hi,
I am a college freshman. I live in the dorms. I have a roommate who has hurt me. At the beginning of the year, we were good friends (in my opinion). We would do things together and talk a lot. Then I don't know what happened but she just stopped liking me/wanting to spend time with me. I don't know how to act around her. Since nothing discrete happened (we haven't fought or anything), I never confronted her. I thought if this girl doesn't want to be my friend, I'm not even going to make the effort to repair the relationship. So far when I have to see her I'm fake nice, but that doesn't feel good because it's fake. I don't want to be mean though because I know that wont feel good either. She's hurt me... and I just don't know how to act around her. How do you guys act around people who have hurt you in the past but you have to continue to see? I don't think I want to confront her because then that will give the impression that I want to be her friend and I want her to start including me in stuff, when at this point I don't because I don't want to be around people who don't want to be around me. I just need a new technique to feel okay about this situation going into next semester. I need a way to deal with this negative energy.
I have been pretty passive and not done anything to assert my power in the relationship - I've just let her hurt me and I've continued to be nice and everything. I kind of want to do something to her (like I brought a TV at the beginning of the year for our room but I dont even watch it but she does so I thought about maybe taking it home...)but I feel like if I do something like that it'll just make me feel worse. Is there a way that I can feel strong and in control in this relationship - and not like a victim who just got hurt by her - without partaking in petty behavior?

You can stop reading here if you want, but if you want to read more details about my relationship with my roommate, like different things that she's done to me and stuff you can read below (totally optional):

She stopped inviting me to do things with her. At first we made friends with people on our floor together... then one weekend I went home and she became better friends with the people on the floor and just all together stopped inviting me when she was going to hang out with them so I was alone (since I have made other friends). At the beginning of the year I was super nice and introduced her to my friends from high school and always invited her out and stuff so I don't know why she didn't repay the favor. whenever I'm going to hang with people on the floor I invite her. Also whenever I'm going to the cafeteria or anything I would offer to get her stuff (i dont do this anymore). At the beginning of the year, we would like each other's stuff on social media... like she would like all my stuff and she would post pictures of me... everyone on our floor said they thought we'd be best friends! i thought we would be too... but yeah now she never likes any of my stuff on social media. after she stopped liking my stuff, i had continued to like her stuff just to be nice and to hopefully get her to like me more, and she still didnt like my stuff so i stopped liking hers. i had to unfollow her on all social media because it was just negative energy every time she popped up on my feed. I was also really nice because her boyfriend has come in town a few times and I went out of my way to sleep in other people's rooms so she could be alone in the room with him. and when we talked about it i didnt just say "yeah, fine, I'll sleep somewhere else tonight" i was super nice about it - because she was saying how she felt bad kicking me out and I told her that I didn't mind at all and that I was happy to do it.

i just cant tell with her! she's a nice girl ... like she's never said anything outwardly mean to me, but her actions have just been really hurtful.

To me it sounds like honesty would be the best. You wrote about how you're not comfortable with confrontation but I can't see anything changing unless you communicate your feelings to her. She may not even realize that she has hurt you.

I think your passivity is noble but also part of the problem. I say get your feelings out there in a calm manner before they force themselves out in increasingly negative ways.

I think the only way forward I would like is to discuss the situation, tell her you perceive her as changing and ask her has she and why, ask her if you did something/if she is mad at you, etc.

I had a roommate like that, that I got along well with and then she suddenly got snarly and it was because of something someone else had said about me, some things she had taken the wrong way, etc. You do not know what happened that weekend you went away, who said what about you or you and her relationship or what went on but obviously something did? If you can calmly explain how puzzled you are at the change you feel happened and wondering about it, etc. without being blaming, maybe you will learn someone else said something or one of your other friends said/did something or someone knows someone who knows someone, that sort of thing and you can at least know what you are up against and what has happened? Maybe things will get a bit better/less awkward and maybe not but some of the feeling of uncertainty will at least be gone so you can feel more neutral?

Why not write to her instead of a verbal confrontation?

Email her and tell her what's on your mind without being accusatory. Just say you've noticed the dynamic has changed within your friendship (provide timeframe and an example like you did here) and you would like to know if there is a specific reason for that...

I prefer written confrontation, I'm too aggressive during verbal ones and I don't have the same amount of time to think before I speak...

I don't think you really need to do anything - other than be civil. You're not obliged to be her friend and clearly she's had the same thought. This can happen at the beginning of college, people will cling to each other whilst they're getting used to their surroundings but find out that actually they have little in common or don't really like each other. It's normal - and also a pain to deal with. If you don't want her friendship - carry on and find others, all that wasted energy thinking about her could be spent finding others who will want to know you.