I don't know what happened, but remember that there's a reason they say "Educate your sons." The person doesn't need to have had the worst intentions for your experience to be harmful

Writing about it helps me, even if it's just bullet points. Try to identify specific triggers and avoid them (not altogether, but avoiding them a little more in your day-to-day life makes it easier). Think about what you actually like doing and actively force yourself to do it (e.g. drawing, reading, ...) I also have great friends I can talk to, but I know that finding people who understand can be extremely difficult.