Where's your DH? Have him confront this clod. He is there to protect you...put the load on him.
This type of attitude has always bothered me, especially on this board when it comes to "Well, it's his family, have him talk to them." Please note, The Ricker, that I'm not disapproving of you personally, just that it is an overall attitude of which I disapprove; you just happened to be the one to broach it.
This is her problem, not her DH's; if he feels the need back up her, that's great, but he should be the back up, not the vanguard. If talking to her BFF doesn't work, then she needs to confront him herself.