I spoke to my sister (close friend since childhood) whose brother recently married and she told me that she and her sister-in-law have also had their moments as well but that I just had to be the bigger person here though she totally understands how I feel. She also acknowledges that I'm not wrong to feel the way I feel that what my sister-in-law did was petty but that's how the game is played and I can respect that.
She's met my sister-in-law and knows her nature as do I and she told me that for whatever reason my brother fell in love with a jerk, I'll have to learn to tolerate her and that it's my choice whether to isolate myself or not but ultimately that it'd only hurt my brother, which there's a part of me that's concerned about that and a part of me that isn't because he knows what the problem is and hasn't done anything about it although he recognizes that it obviously upsets me.
Yeah, I suppose I am a little jealous but right is right and wrong is wrong and she was wrong. I, however, will have to let it go. So again thanks for everyone's advice and the different perspectives though we'll just have to agree to disagree. Thank you, Bookmiser, for understanding where I was coming from; you always cheer me up
