"I'm sorry. I have PTSD" kneejerk reaction

I am an agoraphobic shut-in. I go to therapy, but besides that and maybe once a month of errands, I don't really get out. cPTSD is part of what made me agoraphobic. When I get out, I have this intense urge to apologize to people for how I am. Later, I will logically know I was just being a normal (albeit probably tense, anxious, and scared-looking) person, but in the moment, I don't really think of that. When I have to talk to people, I get this kneejerk reaction to tell people I have PTSD (since complex PTSD isn't well known here) and apologize for myself, like I'm some freak that should feel ashamed for my existence.

I wish I could say I want to break this habit, but something about it actually makes me feel better. It suddenly makes me feel less tense after I say it, like maybe they will understand. I also have super bad body dysmorphia, and I think I look like an ugly, inhuman creature to people. So some part of me gets this feeling of "If they know, maybe they'll understand why I look like this." I've been told I look like a normal person, even pretty, but body dysmorphia can't just be waved away with logic, either.

Anyway, I was just wondering if anyone else got this same kneejerk.

Also, as a positive note, I had to get out today to the DMV. I felt almost normal for a little while, and when I noticed people looking at me, my mind didn't distort all of them into thinking they wanted to hurt me. (A couple of them near the end started looking suspicious, but I got home now.) Most of them even felt flattering a little. I felt human.