I have a restraining order against my daughter's father. I also have full physical and legal custody of her with supervised visitation that he never uses. If it were any other way, I wouldn't be able to sleep at night.
I'm sure our situations are different, but FWIW, I would not leave the kids alone with him; I would contact an attorney immediately; and I would absolutely go back and fight for supervised visitation. His "excuses" for not using the soberlink indicates he is drinking. The accident indicates he is drinking and driving. It seems it's only a matter of time before he does both with the kids in the car. It's better to be safe than sorry.