i think you have shared some of this situation with us here before. i commented then, and i will repeat now, you have to do what is best for your children, for your nuclear family. yes, you love your parents and your brothers, but you CANNOT put your children in the kind of situation where instead of singing Here Comes Santa Claus they will be humming the theme from Cops as Uncle Bubba is taken down, cuffed, and hauled off in the paddy wagon (and to the poster who doubted that the cops will be lurking outside to do just that, don't. hell, even Al Capone probably went home to see his mama for Christmas. where else are you gonna find them easily?).
it's wonderful that your parents have found each other again after all these years, but your mother seems to have some Norman Rockwell Christmas scene in her mind. it seems to be clouding her judgement. if she could adjust what she wants to include protecting your children, fine. if not, then you are doing exactly the right thing for your beautiful boys. your kids, your call. it's not at all fun, i've been there, done that. but it's the right thing to do. if it helps, WE love and respect you!
editing to add, responding to your posting that your parents are hiding your brother and not telling anyone where he is. well, they've chosen which child they will spend Christmas with.