That's pretty good, having your FIL as an ally. My FIL, I believe sensed something going on, though he never mentioned it, and we never told anyone. He was an ally for me, telling H how hard M was, and how it would be easy to give up, but that after he had been married to MIL for a long, long time, it got easier. He was a doll, and I miss him.
I am glad om isn't brought around your kids, you don't need that!