I'm working through establishing boundaries as well. I have a good friend who seems to know hers in black and white and she is always surprised when I tell her what I've put up with.
My most recent boundary came when I was driving with the xABF and he almost fell asleep at the wheel after having pounded a few beers and smoking some pot before getting in the car. From that moment on I said I would never ride in any car he was driving in when he was drinking.
Now, although that boundary felt good for me to say, when I told my therapist about that today, she praised me for having it but then asked what should I have really done? The answer was I should have dumped him right then and there.
We are so skewed with these AR's that I don't think we take things as serious as we should. I know that when I first started my R with xABF the red flags were there and I knew what my boundaries were then. But, little by little I stopped reinforcing them because he was so good at making me think what he was doing was okay. And, that I was okay.
I did tell him what my boundary was because he wondered why I didn't want to ride in the car with him anymore. But, it also became a challenge for him to see how easily he could break it.