It's hard isn't it. I have now got fibromyalgia, which I think is partly the result of living on heightened cortisol levels for so many years. I too have some symptoms of PTSD although I am not diagnosed.
It's easy for them to pretend that they're better behaved now (so you end up believing it's your fault they were so awful). Just remember it's all a facade, the mask slips eventually and you already know the truth.
Once your DCs are adults, you'll have less to do with the ex. My contact with my child's father is minimal to non existent now, having sat through a graduation and wedding. They can see him for who he is now, I didn't badmouth him.
No DCs with the exh fortunately so no contact required there but the cumulative effect of those two relationships have affected me greatly.
The best revenge is to live your life well and be happy with your current choices. Try not to be bitter, it's not going to help your physical or mental health. I truly believe that everything happens for a reason and we can always learn something, even if it's 'don't do that again!'