Addiction and mental illness go hand in hand. His relapse rate will likely be high unless he is willing to only take his prescribed medications, nothing else, and never ever drink, forever. It's a big commitment not a lot are willing to make. I don't say that to be mean or give you anxiety, it is just that if he truly has Bipolar, it's very very hard to treat, and goes hand in hand with addiction, as you know.
You know the right thing to do, just what you said. Keep using your rational brain to make decisions. I hope you have support for you and your children.
Many, many hugs to you.
Hats off to you to call the police. You did the right thing, he could have killed someone, or himself. I want you to know my X said the same things to me, that he was going to drive into a tree so our DD's did not know he tried to commit suicide. While I take things seriously, I can say, that has never happened. For him, it was a manipulation tool to keep me in our marriage and for me to continue to enable him.