FIL “Drama”

Recently my MIL passed away. She was a pretty vile woman and she was abusive to my husband and my SIL. They haven’t really expressed sadness for her passing and their father isn’t very happy with them. He thinks even though she put them through a lot they should still be grateful for her and should grieve her. He has told them they are being childish and overreacting to past events and they don’t have trauma. He calls it “tough love” . My sister in law even has memories of her mom trying to sell her (sexually, to degrade her) and my husband has said that she was mentally abusive to him and he never said anything and she said boys don’t cry. She was never the nicest and she also was pretty mean to me. She wanted her kids to always be dependent on her so she always tried to scare away their partners. This is causing chaos in our lives because everyone is kinda fighting each other. I don’t wanna intervene but I do want to be there for both of them. He’s pretty old fashioned but kinda puts everything aside. I personally think maybe her ways affected him too and made him think that maybe she was right. But then again he is a grown man and should protect his children. I don’t really know how to feel because I’ve always liked my FIL but after this, it kinda seems they were made for each other.