If what you think is true, that your H is all about the chase, when is the last time he's had to chase you?
I want to be clear as you move forward through this, IF he is MLC, consistency for him may not be something that you can look forward to, for a while. IOW, if he seems to be pushing you away right now, he might start chasing you at some point and then go back to pushing you away. For no changes that you've made.
What is going to be really important though, is doing your very best to "keep the road home paved and smooth". IOW, even if he's MLC, he'll remember stressors, even if he doesn't remember specifics. Not saying walk on eggshells, rather that you need to ignore bad behaviour and appreciate good behaviours from him. He will understand and remember the loving behaviour in the even that he considers coming back.
So, that said, do you make sure that you look and act your best when he's around? If he isn't seeing your attractive features and that you are not just available for him at a whim, perhaps he'll start chasing again. Is that something you would consider and how might you princess yourself up? Could you "do" the cowgirl thing?
As far as things building to a climax quickly, the best thing you can do is detach. Understand that while sometimes things do happen quickly, if there is no pressure to the WAS/MLCer, they seem to slow down in running away. You possibly have more time than you think.
On him drowning? There really is nothing you can do. You can put the water in front of the horse but you can't make it drink. He may only seek the help he likely needs if he hits bottom. It hurts to watch that, but there really is nothing you can do.
You are only responsible for YOUR parts. Did you have an A with his brother? Yes. Did you contribute to the breakdown of the M? Certainly. But you contributed. He certainly has contributed his share. You can only work on your stuff, you can not help him with his. Try to find your middle ground on that.
Again, the only think you can do, and remember that you have the kids to share with him, is to go as "dim" as possible, while remaining open, pleasant, and become the "catch" that he really wants. That can help get you to a point where he might question his motives. He might realize that you are an amazing woman that only a fool would leave.
After that, if he changes his mind and wants to come back, THAT would be when the two of you work out your joint issues. Until then, you need to work on yourself and become that even more amazing woman that only a fool would leave.
