if his personality just recently changed, you may want to get hi checked out by a vet. he my have a brain tumor which is causing such a personality change..This is a big 'IF". just a suggestion so you rule everything out. if not then u may just want to put him down as a safety precaution.

OP, why have you kept an aggressive dog in your house along with your small children? You do know that dogs aren't people, and your children should come first. Right? Right?? I feel awful for your children, and I hope they don't get seriously hurt while you're waffling around trying to figure out what to do with this dog.