If we react to others defensively by attacking or withdrawing, conflict often increases. If, instead, we respond assertively we can help to bring the conflict to a level at which emotions can be reduced and negotiating then becomes possible.
Saying "enough" or "I don't want your anger". Firmly putting our hand up as if stopping traffic. Everyone has the right to say to someone else that they are angry with them. No one has the right to be abusive and aggressive with someone else.
Making an "action-response-outcome" statement. The three parts of this are "When you ... I feel ... and I ask that ...". This is saying how someone's behaviour leads you to respond and what you want to happen, e.g. "When you break our agreement not to use drugs in our home, I feel so angry and exasperated with your behaviour".
"I ask again that you honour what we agreed". What is important is that action describes the user's behaviour and not them as a person, response is about your reaction and outcome is what you want and not just a demand.
Being a 'broken record'. Keep repeating what you want and don't let yourself be deflected away. "I know you say you are making an effort but I still find myself having to deal with your bad manners".
Compromising or playing for time now and negotiating later when dialogue is possible.
If all of the above feel too much of a risk because you feel threatened, then withdraw from the situation. This could be anything from a few moments apart to ending all contact.