Why has he had an issue with your mom? If he's stepping over the line, then maybe you need to stop him. Not necessarily argue with him, but tell him that regardless of what is personal feelings are, she is still your mom and deserves respect. She's the one who is going to be there for you after he's gone after all.
M-43 W-40 2D - 9 and 5
Emotion, yet peace. Ignorance, yet knowledge. Passion, yet serenity. Chaos, yet harmony. Death, yet a new life.