I hate that girl so passionately?

I have a boyfriend and hes been spending alot of time with a girl that i dont like. I cant tell him to stop talking to her because i dont want to look like th villain. His mom is now bestfriends with her and inviting her everywere. Ive been in this relationship for a year and have been working too hard at it for some girl to come and suddenly ruin it. Ofcourse im jeolous but i cant show it and its eating me inside that the mom is suddenly bestfriends and takes her everywere near my boyfriend. what should i do?