Wow man, I am sorry you had to endure that (both the actual event, and the emotional pain of the flashback). Heartbreaking stuff.
I can imagine that, being a father, you feel like you need to be strong and faultless for your kids (and
their kids??). But I am concerned that if you ignore this flashback, if you try to pretend it didn't happen, chances are really high that it WILL happen again.
I know you're on the xanax, but are you getting any therapy at the moment? Have you ever had therapy for PTSD before? If so, how long ago was that? I really think you should strongly consider going back in to therapy. If you face these memories and work through them in constructive ways, you will be much less likely to have these violent flashbacks that come without warning. You went through some really fucking horrible stuff, but it doesn't have to control your emotions or your life. The memories are in there, you can't change that, but you
can change how your brain and body react to those memories.
What do you think?
Take care man