I don't know what to do!!! What should I do?

've been in a relationship for about 7 months now. Two months ago I found out that my Bf's ex had come to visit him asking him for help. The way I found out was through a message on facebook that she had sent me talking about how my Bf is her bf and I should leave him alone, that he goes home to her blah blah...now I'm not the type of person to snap or jump into conclusions. I talked to him asked him who was this person and he confessed. I asked him if he was going to continue seeing her and he said that, well she has nobody no parents no relatives etc...the close thing to a relative was him and his family. So he told me he doesn't want her in his life, but he feels obligated in someway feels pitty for her. I honestly do not know what to do I mean I love him and I'll stand by him, but I don't think he will ever push her away . Shes very immature and dramatic. What should I do? Some advice please.