I feel a lot of compassion for your husband. This situation is hurting you - it really is - and I feel compassion for you too. But this infatuation and the decisions he's making right now aren't the behaviour of someone in their right mind. Was his relationship with his adopted mother poor? Is she still living? This has clearly thrown him for a loop. It doesn't mean that the problems in your marriage aren't real, or that you don't have 180s to do (we all do - I'm not sitting in judgement here!) only that he's clearly not in a position to be repairing or restoring a marriage right now. I think you're going to have to sit back, sit tight and wait for this relationship with his mother to either implode or stabilise.
Do you have a church or synagogue or mosque or something like that? I don't advise that you tell tales on him or anything, but this man sounds like he badly needs the support and guidance of another man who he respects. You can't arrange that for him, and I'm not suggesting you manipulate him into pastoral counselling. But you don't need to keep what is happening in your marriage a secret if that isn't in your best interests.
