Help sister in law problems?

My husbands sister who is on the dole regularly has one night stands after a nights out and has also had an on/off affair with a married man for almost twenty years. So what with that and her binge alcohol drinking i do not have much respect for her as I am a clean living person. My husband puts me under pressure to hang around with her but i find her behavoir embaraasing as she is loud and gets banned from places because of this. He cannot understand that I do not want to be around that and because he respects her so much, I am wondering if he is up to her tricks now also. I am very confused and of course I love my husband what shall i do?