I don't know if you could really call that guy an "ex-boyfriend", if he was much older and you started dating and living with him at 16. It just sounds like he was a predator in the first place in my mind.

Anyway, I have flashbacks even when my 1 year old son touches me on accident. I found filling out a PTSD response worksheet right after a flashback or panic attack somewhat helpful. You can find one online. I only did it a few times so far, but it helps you realize why you were triggered and what you were thinking was happening. Like when my son accidentally touch my rear with his foot when he was laying down next to me, I was not in danger. I was in a safe, okay, accidental situation, but I was triggered to a memory of a past dangerous situation. These worksheet will also help you realize that you are usually not in any real danger when you have a flashback or panic attack.

You can also go to therapy at a center that accepts sliding scale fee or a non-profit organization, like Call Rape.