Mom trying to force me out of relationship.

I have been with my boyfriend for over a year. My mother doesn’t like him simply because he smokes weed. My mother says things to make me feel bad. Saying things like that I don’t love her and don’t respect her when I do it just doesn’t make sense to break up with someone over smoking weed when I do to. She says that he is the one who started me smoking but it’s not true. My mom is a former crack addict and she says that she started with weed because weed is a “gateway” drug and she believes we are going to smoke other stuff and that’s bullshit. Just because she did it doesn’t mean I will. All of this is taking a toll on my relationship. When my boyfriend comes over she just makes him so uncomfortable that it’s putting stress on our relationship. He is so respectful to her but she just acts like such a bitch! It’s to the point he doesn’t want to come over and I can’t even blame him. Who would want to be somewhere when there clearly not welcomed. She even brought my ex into a conversation talking about how much she liked him and my boyfriend was right there!! I love her and I want to make her happy but I don’t want to risk my own happiness in the process. What would you guys do? I’m so desperate I could really use the help.