Help being more confident and/or social?

Hey everyone. My girlfriend broke up with me a couple of months ago after nearly two years, I've been trying to cope with being single but it's really starting to get to me. She's with her second boyfriend since our breakup, and I haven't been with anyone since. Partially because I don't see anyone at school that interests me, but I'm still single. I don't want to be with just anyone, because I wouldn't be happy and I'd wind up breaking her heart.

The real issue is, she made me feel so confident and so amazing, when she broke up with me that's slowly been crumbling, and now I keep looking down on myself. She's still pretty and confident, and I don't feel attractive or interesting or anything. The only thing I see that I have going for me for looks is that I have great hair. What am I gonna do with just that? And the fact that I don't talk to many people (not to be ignorant, but only to people who aren't as smart as me, and therefore I'm not truly interested in any girls I talk to) and I don't do anything out of school doesn't help me at all. I'm looking for somebody that's smart and kinda nerdy, because that's who I am. I'm not asking for a girlfriend though this post, that'd just be weird.

I'm rambling on and on but I'm really looking for some support, tips to make me feel more confident or tips so that I can come out of my shell, I want to feel somewhat attractive and confident. I don't like who I am (but I feel like I should) and I want help feeling better. If this makes no sense, that's ok, I don't feel like I ever make sense.