I'm also from Eastern Europe originally, although I live in England. FWIW my advice would be to make friends with someone in a big organisation like MSF or the Red Cross, and talk to their volunteer support. This is a common problem for people who work in war zones, and they can't adjust to "normal" life. Most big charities have support systems for this.

And BTW, my 84 year old mother sometimes still gets flashbacks. Not bad ones, not often, but she still remembers. Some things never leave you.

If you like reading the psychology literature, there are a lot of good books written about this.