you may want to consider the current living arrangements in the larger picture.....you are already connected to your AH for the long haul because of the kids......continuing to live in your INLAWS home just keeps you further bound to THEM. you have mentioned that your relationship with them is already dysfunctional....and i assure you, it isn't going to get any easier.
i only suggest that you CONSIDER new living arrangements.........that are not tangled up with HIS family. you are going to want and need breathing room....being dependent upon HIM or THEM will hamper that going forward.