Worried I lost my best friend

For context, I'm a 20-year-old virgin, borderline socially retarded (I'm diagnosed with Asperger's), severely depressed, and a loser in general.

I've never had a "girlfriend" or even met a girl who seemed vaguely interested in me. Most girls ignore me and the ones who don't get really uncomfortable when I try to get closer to them. I don't even get "friendzoned," I've had about two friends who are girls in my life.

There was a girl in one of my classes at college who would always sit alone so I decided to talk to her. We got along really well and had a lot in common and became friends pretty quickly. I wanted to date her but she has a long distance boyfriend but I was happy just to have a good friend. We'd hang out a lot and eventually we started being affectionate with each other. We'd sit down together and we'd cuddle and hold hands. I know it probably isn't really great to do that with a girl who has a boyfriend but I didn't care, it just felt so good to finally be intimate with a girl.

Eventually summer started and we had to say goodbye. We were texting each other for a while but eventually she stopped responding. I texted her again a few weeks later but she never responded. I was always worried I'd lose her like every other good thing in my life and now I'm starting to feel like this has finally come true. Maybe I did something that scared her away somewhere along the line or she decided we were getting to close to begin with. I have other friends but they all think I'm weird and awkward whether or not they like me and she's my only friend who I really felt understood me.

My worst fear is that I'll go back to school and text her to see if she wants to hang out like we used to and she'll never respond. Sometimes when I'm sad I just think about the times we spent together like when we worked on a project for our class and really talked and connected for the first time or when we curled up in her bed together and held hands. If I lose her all of my memories of her will become painful.

If I were just a normal guy I'd make other close friends or find another girl who wants to be intimate with me but I've been trying to do those things for a long time and I honestly don't think I can do either of those.

The reason I'm posting this is because I saw something on TV that reminded me of our friendship and it made me feel really bad. What do I do?