You are correct that is a dangerous situation. And I suggest if you cannot come to terms with the husband, you have a right to make your son stay at home. Of course, as you know, that will only cause problems with the Father.
If possible, I suggest you will have to have your son call you when leaving the friends house for you to pick him up - and then you also can time the call to the police that he is drinking and driving. Additionally, if you know that he is on his way home, you can call the police and have them be waiting for him when he pulls up. They can charge the DWI even if he is sitting in the driveway
with the keys and does not actually have to be driving.
It is unfortunate for your son because it sounds as if the Father is going to do what he wants regardless.
Absent a legal separation where you get full temporary custody he has just as much right to take your son with him
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