On the PTSD note I have read articles which compared the stress levels and brain chemicals of friends and ESPECIALLY family members of substance abuses with that of SOLDIERS in ACTIVE WAR ZONES. Guess what? They were MORE than comparable. They were the same. That just made me actually feel better because it was like I finally got validation for what I felt and how stressed and terrible.
I don't think you are wrong to set boundaries with your children. Not at all. Self preservation only looks mean when people can't see past the end of their own noses.
I had a friend who was in a bad relationship once. A hysically abusive one. I moved her completely out safely in the absence of her fiancée. I opened my TINY home and life to her. The day we did it she spent all night crying and finally begged me to take her back. So I made a deal with her. I said I'd take her back and move all her stuff back in too. I promised he'd never know a thing I'd move her back in so well (and he never did) but on one condition....if I did all this I would NEVER come for her again. This was it. This one time. And she agreed. And she went back. And she got the stuffing beaten out of her until she finally left him for good after a couple more years. But true to my word I never helped her again. And true to her word she never asked. Yet somehow, some other way, things worked out for her to leave on her on time. And I never once felt guilt about that. Because that was HER decision.
You sound like a wonderful momma. Don't allow yourself to be badgered into believing otherwise.