1. Never contend with a man who has nothing to lose.
2. If you are in an abusive relationship, establishing boundaries may not be possible, as assertiveness in sharing your boundaries may not be even safe. And because the other person has a distinct agenda of controlling or even hurting you - you'll just get laughed at - if you try to voice your limits.You may need to consider leaving that relationship safely.
3. Voicing a limit or a boundary is not the same as a demand. It's telling someone what you prefer, where you stand on something. You are not demanding anything, or telling them they are wrong. You are just asserting your own values, your desires or your limits.
4. Sometimes the boundaries need reinforcing from time to time. This may sound like a parent-child relationship - and it is that way. But we are not doing it in an authoritarian way, we are doing it in a friendly, supportive way. But we are also being assertive about our boundaries being understood and respected.