Been there, done that.
Here's what helped me:
You need to substitute a healthy behavior for the cutting. You're doing that to deal with the anxiety, yes? Try running. You should start a running program every morning. Get up early to do it. Every time you feel like cutting go for another run. It will help with the depression and help blow out the anxiety. If you can't run, get a couch to 5k training program and learn to run. Biking or swimming or any other hard aerobic exercise is going to help. This will start helping in the short term. If you do it regularly, it should start helping right away.
You are already taking an SSRI medication. (Zoloft, Prozac, etc.) They are excellent for relieving the type of anxiety that you are dealing with. If they are not doing enough, you can change medication or change dosage. Talk to a doctor. You may need to take a different kind of medication, like Wellbutrin.
Take a holiday from drinking and going out where there will be boys. Start showing up for house events that don't involve those things. You bond with people by spending time with them. Spend time with your sisters doing things that don't involve alcohol or boys.
I guarantee that other women in your chapter have had sexual assault experiences. In my small chapter, several people had those experiences. About 25% of college women will experience some form of sexual assault. It's not your fault and you're not weird for having this happen.
Give yourself time. It may take a year or two to settle down.
Counselors didn't do much for me, frankly. I got a lot more out of Albert Ellis' self-help books. Ellis founded a school of psychology called Rational Emotive Therapy. It's a sort of DIY cognitive behavior therapy. It was really useful to me. He has a tone of books, but you might try this one:
http://www.amazon.com/Overcoming-Des...1&sr=8-3-fkmr0
Also, I had to quit drinking entirely. About two years after my rape, I decided I had a drinking problem and went to AA. I spent a long time in AA. It helped me, but I had access to some very good AA groups and groups with young people in them. There's a lot of bad AA out there, so it may not be helpful to you. You also have to watch what group you join because I've known women to be revictimized by male AA members. It's 18 years later and I'm not sure I was an alcoholic. I do know that drinking triggered my PTSD, though. I would barricade myself in my room when I drank. I just can't drink anymore. (I was pretty drunk when I was raped. Not too drunk to run away or say "no," but too drunk to stop it.)
You may also not be alcohol dependent, even though you're drinking too much. If AA isn't for you, you might want to try Rational Recovery (read the Little Book). It can give you strategies for quitting drinking abusively without declaring yourself alcoholic. Women for Sobriety is a great group for women that focuses on building women up, rather than the "ego deflation" that is one of the core principles of AA . Moderation Management might also be worth a check.