I hope you can find some counselling, and work on these feelings so that you can continue to have a strong and wonderful relationship with your son as he grows up.
From what you’ve written, he sounds lovely, and you should be proud of him. And proud of yourself too that you’ve brought up a respectful young man who’s open and comfortable talking about his feelings with his teenage crush, and comfortable to wait for her - which is great!
I can feel the panic, horror and disgust in your posts. That’s your past trauma triggering and it just rising to the surface and taking over. That must be horrible to be experiencing about your own son. You must be so panicked and upset. But it’s ok you know. It really really is. 
Your son is not his father. Your son is not a rapist. Your son does not even know how to think like a rapist, or behave like one. He’s a lovely boy who’s taking his very first tentative steps into romantic relationships. A kiss. Which he is happy to wait for. That’s sweet. And lovely. And not ugly and scary or terrifying or dominating.
It’s all mixed up in your head at the moment, and it’s great that you recognise this. Look how strong you are... even though you are feeling all these terrible and devastating emotions and triggering memories, you are still fighting to make sure you do what’s right for your son.
That’s powerful that is. You’re powerful, you are.
I’m going to stop on that note because it’s important you hear that, but I’m also going to write another post about practical stuff about ptsd and trauma x
But, for now I just think it’s SO important that you recognise the good and the power in you, because this thread has been written when you’re so vulnerable and exposed and battling such awful trauma, it’s easy to focus on the ‘what’s wrong with me’ bits and the ‘I’m going to fuck up’ bits and not see the amazing job you’ve done so far, and how great it is you’ve come to this point in spite of all the crap you’re carrying with you that you’ve experienced, and that you’re determined not to blindly pass on to your children.
Well done
. You’re stronger than you know to have come to here.