Would it be okay if I avoid conflict with my mother's boyfriend?
If something happened to them what would you do?
If anything happens I'll let them fight it out on their own.
As you should, her boyfriend may still be quite unknown to you and he might be dangerous. You need to steer clear as it's all your mom's problem and none of yours.
I did not want her to go further, but letting her fight her own battles is all that I can do.
It is fine to avoid conflict and handling things in a more constructive manner is always good and healthy. I'm proud of you!