Please help!!!!

So my boyfriend is really close to his best friend and they pretty much live at each others houses. I'm pretty good friends with his best friend too, us 3 hang out a lot but I still get a lot of alone time with my boyfriend. The problem is that my boyfriend's best friend's mom HATES me and I don't even know why! I think she feels I'm a threat because sometimes my boyfriend chooses to go out on dates with me rather than hanging out with her son. The first time I met her I shook her hand but she kind of gave me the cold shoulder. I've been nothing but nice to her every time I see her! I honestly wouldn't care that she hates me besides the fact she's really close friends with my boyfriends mom and I know they gossip about everything, (probably including me). She even went as far as claiming I got my boyfriend into drugs and telling my boyfriends mom he should break up with me! That's so absolutely ridiculous, I've never even touched drugs....luckily my boyfriends mom set her straight but I'm worried that if she keeps making these outrageous accusations that my boyfriends parents will hate me too! What should I do? Is there any way I can get her to like me????