I understand your boundary and you have to be civil to him because of the children you share. It's unfortunate he's still an angry man, but it could very well be because life didn't turn out the way he thought it would. You've gone on w/your life and have found a way to be happy again. He's still stuck in a rut and miserable and he wants you to be that way too. It's very sad.
Your goals sound like good ones. But please make sure you are doing them for you and not him. Keep your expectations at zero at all times, especially when he's around you. Whatever you do, do not take the bait or drink the kool aid that he may serve up when he's around you. Do not give him any justification for why he walked out the door and you know what, just by being your beautiful self is enough to make him stew in his mlc pot because you are successful. Leave him out there to swing in the wind. I hate to say this, but he might be one of those mlcers that never grows up and stays an angry, bitter man for the rest of his life. Just think, the ow now has the used old man and you, on the other hand, had the best years of his life.
Take care of yourself.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.