Where's that old thread from a year or two ago that discussed the premise that a guy absolutely cannot just be "friends" with a girl?
Tom, everyone's different so I'm not going to tell you what you should do ... but I can tell you what I would do if I were in your situation. And the first part of that is I'd pretty much move on from both Jeff and Alyssa. They're in the past; let them stay in the past. From what you've said, they both pretty much deceived you and lied to you, and it almost seems as if each of them used you. They had your trust and they blew it, and if it were me it'd be difficult to gain back the trust of somebody like that again. The thing to take from the experience is to learn from it so you can prevent it from happening to you again.
Secondly, you're in college, man. I'd get out there and meet some new people. Identify with people who have common interests and just be yourself. You'll find that you'll run into some pretty cool people along the way, and you'll also run into a fair number of idiots. The heck with the idiots, hang out with the people you get along with. Some you may become good friends with, others mere acquaintances.
The biggest obstacle you'll have to jump over in this is being able to trust new people you meet to be your friends and then finding some good, new friends down at school. But if you don't do that, then you're probably going to be pretty miserable.