Sounds to me like he's making a choice, and you aren't part of his plans. You've found out about a couple of his attempts - what are the odds there are more that you don't know about? Do you think this dog knows what to do if he catches a car?
You might have noticed I have a pretty low tolerance threshold for pond scum like this. They tend to give all guys a bad name.
You may have a decision to make yourself in the near future. Wouldn't hurt to prepare yourself mentally (at least) for it when it comes, 'cause you might have to be real tough to survive the turmoil. Do what you have to do to protect you and your kids, 'cause it doesn't sound like that's his top priority.
Maybe you could ask him to help you workout with your martial arts??
I hate to see this kind of thing happen. I watched my mom go through it 45 years ago. It was really hard on her, but she did what she had to do, and it worked out for the best for us.
Be strong, sister!! We're always here for you, you know that!!
CT