Sorry to hear about this son. I feel your wife's brother when hearing what she had to say scared him back into cult thinking. It happens all the time. The pull of the cult is very, very strong. Fear and gulit is their biggest weapon and they use it well. Being born-in your brother in law has been conditioned for years on guilt and fear. It really is no surprise he said what he said. Him sitting on the fence like he was doing for along time then all of a sudden your wife let's him know how she feels really rattle his cage.
Please don't take it personally you have to pity him, he is a victim of a concept just like all of us at one time. Give him time maybe he will come around one day. Just remember you guys are doing the right thing and just like your mother said we are there for you. Try to have a good day we will be thinking about you. Still Totally ADD aka dad