<human>: So ever since I've been seeing my girlfriend of two years she and her family have expressed discontent with her brother's on again off again girlfriend, we'll call her Michy. 

She is a horrible person who everyone is pretty sure does not actually love her brother. She uses him for money and sees as many guys as she wants using them for money and sex, even being engaged to one guy she has no intentions of marrying) but still maintains some sort of relationship (if you could call it that) with her brother because he is the most devoted to her. And the worse part is he does not seem to care. She uses him and sees other people but as soon as he starts to veer off her path she comes back and sinks her claws right back in to him in a succubus-like manner. 

He's in the Navy currently so he's away most of the time but whenever he comes back you can be sure you will see her around as well. Their family (minus my gf is mom, dad, sister) has even gone to the extent of voicing their distaste of her and banning her from their abode. Her sister has even almost gotten to a fight with her but they still have not managed to shoo her away.

If her scandalous and philandering ways weren't enough to leave a bad taste in your mouth she also tries to imply to their family that he loves her more than them and will talk about her sex life with him openly and nonchalantly with them around. She has also said she wants to get married to a few rich guys, get divorced and eventually settle for him. It is just so twisted how she could feel that comfortable admitting all these gross and ugly things to them like they wouldn't only wish the best for him and his happiness.

The past few days my girlfriend has been getting extremely riled up about this even to the point of crying for her brother's well being and I was just wondering what can we/they do about this? Meddling too much would only make this worse but is there anything that can be done to help him see the light?

Give me the gist of the text in a nutshell
<bot>: Super scummy girlfriend of my girlfriend's brother is terrorizing her brother and family and I was just looking for advice to help them rid her from their lives for good