Kirsty,

It sounds strange, but at least you know now. The uncertainty is gone, even if it is not what you were hoping. From personal experience, following you around is trying to see how you react. If you explode, it will convince him he is on the right path. If you are silent and practice DB, he will be left to deal with this all on his own--something he does not want to do. The path of least resistance is to place the blame on you, so don't give him the chance. Regarding the other family....the MLC'er is in fantasy land and thinks the grass is greener. They are convinced their decisions are correct and nobody can inject the truth into the situation.

It is now time for you to pick yourself up and be the best person you can be.

My advice:
-do not engage in emotional conversations. The hangover is too painful and it achieves nothing
-focus on you and your children and be the best parent you can be. Do anything in your power to shield them from living a life with a father making these decisions
-Lawyer up and gather any important documents you can (birth certificates, loans, banking, credit cards, etc) and make copies.
-Do for yourself and give him zero pity. He is out for himself and his wild fantasies only. You will become a better person regardless of the outcome.

You will get through this and will eventually be OK. Like most of us LBS here, I am a year out from BD and am thriving. I never thought I would be here. The folks here are absolutely a godsend so please keep contact here.