I'm going to refuse to visit my mother if her boyfriend is present
Why don't you visit your mom if her boyfriend is there?
She drives me crazy with that guy.
It may be difficult to accept a new family member so late like this, but you still need to give chances to respect her boyfriend. She judged him to be good enough for the family, so you need to come to understand each other to make your mom happy and have a good family relationship.
I hate that guy. I think she's so greedy and wants to start a new life with him.
You should tell your mom how you feel. She doesn't have to give up her boyfriend but you will have said your peace and can move on.