Stop hooking up. Start making friends. Male, female, older, younger, etc. That is, be a part of the world around you, and don't be so overly concerned with whether you'll love again or have sex again or trust someone again. Chances are incredibly good that you will, but you need to open your eyes to the possibilities out there.
I'd also suggest counseling as it's been a few years, and you're still having problems getting past it, and instead are engaging in risky behaviors. Your school undoubtedly has advisors. Talk to one.