Lock every door and window. Put things in front of them that would make noise if they were disturbed(empty tin cans). Call the police and tell them that your husband is currently living out of the house about an hour away but you have some concerns and would appreciate it if a patrol car could swing by your house a couple of times a night. Give them descriptions of his and his parents car if you know them. Keep your children's bedroom doors open. Keep your phone charged and in your bed with you.
Then you just have to trust you've done all that you can and go to sleep. Being sleep deprived is NOT going to do any good for you. If even all those things don't calm your nerves enough, time to head either to a hotel or to your mom's.

You've got to sleep. I wish you well. Sending good thoughts. Call the local police. Get it documented and on record that you are worried.
Be safe. Good night.