Speak to your lawyer about the implications of co-signing for his new house.
How do you think your H is going to do taking care of a house and kids all by himself? I think he is jumping out of an airplane without a parachute and does not realize that the ground is approaching fast.
I wonder if psycho "drive by with radio on" OW is waiting in the wings. If so, I do hope he uses time, caution and compassion for you before introducing the kids to her. It is very tough hearing from the kids about an OP who is taking part in parenting.