Sisters?

My husband and I are here in PA helping out with his mom who had open heart surgery.His brother flew down from Canada and his sister who lives here in Pa have come to be with her till she can get around better.Now my husband loves his mom,dad and brother very much.His sister on the other hand is another matter.She has been angry with him for a long time.Some is because he was (gasp) a big brother and some is because he jacked her husband up for being an ass.Keep in mind my husband is 42 and his sister is 39 or 40.The incident with her husband happened almost 20 years ago.Any way jump forward to present time.She has 2 sons.Loud,disrespectful,lying,destructive,violent,evil monsters who enjoy hurting animals and treat everyone who has the misfortune of being around them like crap.She allows this and refuses to allow anyone to so much as say no to them. Insisting she will raise her kids her way cause her childhood was so bad and she will keep them from that.So for the last 2 days they boys have been here at his parents house with all of us.This evening his sister became offended when my husband and I said the boys could not have yogurt that was bought for my father in law.So she proceeded to tell my husband off loudly in front of her 2 delinquent bastards. Angry that someone said No to her kids.She stormed off in a huff after making a huge scene and saying she will not come back as long as we are here.Which is a blessing for us.This is not the first fit she has thrown,but it is the first she has thrown around me.I did not say a word because I did not want to upset my mother in law.
  We have been up here a week and every day it is harder to stay and see how my husband is separated from his family.They treat him differently and they constantly bring up things from his distant past to put him down.All in front of our 15yo daughter who is here with us.He doesn't let me say anything and it is so hard for me not to.I am not someone who can hold my tongue well.This trip has really shown me how much his family judges him and I know why he chooses to live hundreds of miles from them.It also illustrates the difference between family and relatives.