Firstly, I'm sorry that happened to you. That must have been horrific. Not something that just goes away.
Secondly, you owe it to yourself to find a good therapist who can help you with this. Both the PTSD and helping you feel stronger and better about yourself. Therapists have seen everything. You talk, they listen. NO JUDGEMENT. Then you can make decisions about what you want to do next. From a position of strength, with support from someone who's trained to deal with situations like this.
If this was when it first happened, I'd be the first to say leave and get to safety now. But this is 20 years later. Not saying it couldn't happen again, but if there hasn't been another incident, you likely have time to set up an appointment. You're the best judge of that.
Don't delay making that call, though. The sooner you start, the sooner you'll be able to decide what you want the rest of your life to look like.
And lastly, once you feel better and stronger, if you and your therapist agree, you can bring him into sessions so you can discuss your fears, your feelings, and the future in a safe environment.
Good luck and I hope one day you can be free of the hypervigilance and fear. You've held it together all these years; now it's time to make life about you. 💜