Let me keep this short and sweet.
(1) Protect your hubby from nasty sister and show-off boyfriend. You wouldn't let someone else do that, why should "family" do that and get a free pass?
(2) Move out as soon as possible. Living together is the cause of so many family quarrels.
(3) Rule of thumb: If it concerns his side of the family, let him deal with it. If the issue is coming from your side of the family, you deal with it. More problems if it is the in-law talking back to the family member.
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