BM drama

my SO and I have been together for a year and throughout our whole relationship his bm has been a bog problem. she blows up his phone all the time but its never about their child its always her trying to get back with him. then when he does try to see his child she tells him no bc he won't get back with her. she has pulled up at my house (had to fight her that day). I love him to death but his bm is really getting on my last nerve. Any advice on how to deal with the situation??