Out but unresolved problems

The quick version. I spent all of middle school, high school, and most of undergrad doing everything I could to hide being gay (not unique I know). I went through a lot of rough phases. In grad school everybody knows (except my family), but I'm still having problems. First, I always thought I didn't have people to sit with in classes because I was hiding so much. Still, even though I usually feel okay now, I realize in a very large class I still don't have anybody to sit with even though nobody else has this problem. I'll even see my roommates then intentionally go sit somewhere else so they don't feel obligated to talk to me (even though we're friends). This gets really embarrassing when I sit somewhere then realize people can easily tell I'm sitting alone. Second, I have a tendency to resort to blaming being closeted for so long for almost anything that goes wrong and that usually spirals downhill. For example, I went out to eat with a group of people, was tired from work and wasn't immediately social, then got extremely nervous and upset I wasn't talking and suddenly felt worth less than all of the other guys there because I was gay. It almost feels like PTSD but that sounds dramatic and I wouldn't actually use that term. I'm not sure if this is normal, if it's related to a lot more than being gay/closeted for so long, or what's going on