How would you handle this?

I don't understand why you are not willing to sue? You obviously need to have a talk with them tell them how you feel and point these things out to them.. how it makes you feel unappreciated etc.. but honestly I would have absolutely no problem sueing in this situation.. that is just ridiculous of his so called "parents" and even worse of your MIL to set back and watch it all happen to HER OWN SON! This make's me sick I would sue the pants off of them for everything they owe you and never look back..