My thought is this....your husband should come before your family. Meaning he needs to know that HE is your number one priority. He's developed these feelings for a reason.....so have a constructive talk with him and affirm your commitment to him. If your sister is the source of the problem.....then deal with her directly and make her aware of YOUR commitment to your husband and YOUR family with him is priority number one!
Is he some kind of god? He can't share. He wants it his way. She needs her family and clearly, living with this selfish, hateful child means she needs them even more.
You are not alone. Many marriages end in divorce over family matters such as this. I'm not suggesting that you loose your family over this. What I am saying is that you need to have a serious conversation with your husband about where he stands. You both got here together and you should be able to work through this together without having to choose your family over him and vice versa. Although, HE needs to realize that this puts you in a tough spot. If he truly loves you and your kids, he will work with you to resolve this in a peaceful way. Hang in there, these are tough times and should be easily resolved - I pray that it does.
This has everything to do with your husband according to your details, not your sister. First, I don't understand why you felt compelled to mention your sister's lifestyle. It didn't seem relevant to the story.<br />
Your hubby is a whiny, selfish boy.