Help! im dating a guy with a 3 year old and a baby mama who doesn't know her place?

I've been dating this guy who I'm totally inlove wiTh but he has a daughter with his ex and the ex is non stop telling him how to run his life & its bad enough that.bC she says so I'm not allowed to sleep at his house when the baby is over because their rooms are connected and she doesn't think its right, but ontop of that she's been showing her face around here and crying about how she might have throat cancer to get everyones sympathy, she's just trying to make everyone feel sorry for her and I'm sick of the *****..my boyfriend loves me and does not have any interest in getting back with her but I feel like she's trying to weasle her way into his life again..the only reason she got pregnant was bc she thought hed stay with her but she's a piece of ****..someone please tell me how to deal with this little skank bc I plan on marrying This guy and I need to learn how to get over this ***** being around