What the revert bro should do is stop taking his kids to his mom but keep on maintaining contact with her and being good to her. After all, its not his kids mom and no matter what - its still HIS mother. He must abstain from eating by her but he's a grown up adult and nobody can force-feed him pork and brainwash him into christianity. How many examples don't we have from the lives of the sahaaba where evil was combated with kindness, eventually resulting in another person seeing the beauty of the faith and embracing islaam.