Zelda,
Like you I have a litany of negative past events that linger in my head and are connected to current ones, even if the connection is weak at best. I have characterized them as social "miscues." Part of my way of dealing with this is to get them out there, to discuss what I felt, what I learned as a result. I'm blogging about it and its very therapeutic.
The negatives drive our minds, especially if we are in the high-functioning end and have strong social awareness but equally strong social awkwardness. We know instantly that we do not gel with people, have trouble interacting with them, but do not have enough insight into developing and maintaining friendships. Since the connection is important, but so hard to establish, we tend to reinforce ourselves. When those connections that we do make disappear, it is that much harder for us to take and to try again.
Keep your chin up. We all have good days and bad days. Give yourself permission to feel bad, to feel sad and to hold on to the negatives. Don't try to do it, but do understand that your brain may be wired that way, and while it is frustrating, the negatives do not make you.
I read somewhere once, "You'd spend a lot less time worrying what people think about you if you realized how rarely they do." Its usually far better than we make it out to be.