I'm Lucy, and I'd be happy to answer your questions today. I'm sorry to hear about your situation.
Your husband doesn't have any legal right to make you watch his children when he's at work. With that said, your options are unfortunately very limited since you don't want to leave them alone in the house. You can hire a babysitter. Since the father has shared custody, I'm afraid you can't make him leave without his consent.
Other options here include talking to your husband about your concerns, seeing if he will agree to family therapy or couples counseling to help him understand your point of view, or going to therapy on your own to discuss more effective ways to talk to him. The other option is to move out and/or file for divorce.
A threat has to be a specific statement of intent to physically harm someone or their family. Saying they don't want to do something to you, without more context, is not a threat. If they make specific threats, you can call the police.
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