Loner,
I get that overwhelming want to respond to disrespect in a violent manner. I get that it is instinct. I know there are times for me that it is very difficult for me not to do violence. Especially after I came back, was in huge amounts of pain everyday that messed up how I sleep, and was on some meds that cause violent psycholosis anyway, but the thing of it is you know when you need some help.
You answered yourself here, you got so upset at someone who bummed into you in line, and then that someone laughed about it. I mean you know that is not worth getting upset about on the outside. The dude was a dumb***, and everyone knew it. But seriously man you cannot let him or anyone else get to you like that. How would you feel if you ended up pounding on him, and then found out he was on some chemo that made him super clumsy, and was on so much pred (all to save his life) that it made him have psych issues? (it happens medical issues can jack ya up bad, and people who have them can look quite normal)
Do not allow someone else to upset your calm. So what if someone laughs at you? Granted intruding upon your person is a big boundary, but it was a bump, it was not like you or someone else was actually in danger (and that is the new boundary in your do over), and you got to think about what is more important. AND YOU DID! I am very glad you did! This person is not worth the interference with your readjustment process. Like you said your niece was there and you focus on what she did, said, and looked like in order to get you out of that mode, and you hold on to that, because you do not want to disappoint her or those kids. Think about the example you will be setting for her children and those other boys? You got a do over and you know what your proirities are.
I can only tell you what helped for me and that was actually getting some professional therapy (granted I had to go thru a few mental health professionals to find one that was a fit for me) and some meds. Those flashbacks can be real bad, and sometimes it is a daily fight against not reacting to people who piss me off, but I know when I feel that way, I need to disengage, figure out what is causing it, and find a way to chill, and not let it get to me. It helps if I can recognize my lack of equanimity, and get on it right away it helps alot.
You keep your focus on getting and staying in a good mental and physical space. Glad to hear you are doing that.
Take it easy,
Navy