sorry, but it wasn't someone else's and it wasn't just once, you have a full time full on crack addict on your hands. in your life, in your bank account and around your children.
GOOD FOR YOU for not letting him come home. if you haven't already, rescue the funds, either cancel his cards or close accounts to which he has access. thousands of dollars in 4 days CAN get worse.
i am SO SO sorry. you and your children are in my thoughts. stay safe. do what is best FOR THEM. and you! your H is an adult and if he was such a badass to get all messed on crack, he can badass it right into recovery too. i doubt sincerely that is what is on his mind at this point tho.