Hi Moselle,
they are splitting - black and white - telling whoever they talk to whatever they are thinking gets them what they feel is right.
Besides how I got caught up in this, how do I handle a whole pile of emotionally disordered in laws and make a positive contribution to our marriage?
look at your avartar. It is a small figure. That is you. The world is bigger than you and frankly the picture you have chosen does not even come close to how humongous the world is. You will get squashed it you try to carry it. Don't handle in-laws - you can't outmaneuver them. Handle yourself.
Boundaries - don't trust them with stuff you would not trust enemies with. Be your own man. Focus on what you actually can control. The less you let your actions be reactions to crazy people acting the more straight your path becomes and the stronger you grow. In the end your path will be the sum of your steps.
They are a dysfunctional lot and when the family get together it is a bun fight of parading, invalidation, manipulation and mind games.
Strength is attractive. Validation is connecting. To strengthen the relationship with your wife you can only validate her and respect her even if you don't agree with all the choices she is making at this time.