WTF!!! He had her over to YOUR house, with your kids in the house and didn't have the decency to discuss it with you first? In my mind this was beyond rude. It sounds like they are both trying to push you out completely. Do some tag searches on boundaries and foundations.
This behavior, especially after such a tragic loss, IMHO is a red flag for help. Look into seeking counseling, individually and together. Likely, you both need more attention than the other is capable of giving.