Do I stay in a relationship with a man whose mother won't leave?

My 25 year-old boyfriend and I have been together for almost a year, and for as long as we've been together, his mother has been staying with him (along with her two younger adopted children). It was suppose to be temporary at first, but it seems to have become permanent. She doesn't like me for reasons I don't understand, and he seems to be a little too comfortable with her staying there. When he's with me, she calls him constantly, texts constantly, check up on him, etc. He has even lied to her about where he was when he was with me. I love him and we've talked about getting married, but I don't want to marry a man who still lives with his mother, or a man whose mother can't let go to healthy degree. I would appreciate any advice from real people.

it is very hard to get a son like that away from his mother, it is also very hard to deal with longterm, your marriage to him will never be your own, so give an ultimatum and then if he doesn't come through, cut loose, be prepared to go through with it because more than likely he will choose her over you