It's too bad that things have reached this point, but I myself believe it's better to have a happy and peaceful household for your child. Your ex can still be an involved and loving father, if that's what he is, regardless of living there or not. Though he doesn't sound that involved since he's choosing a video game over his family! Sad.
Since he seems to be agreeable to whatever you want to do, I would GET IT IN WRITING as soon as possible...meaning custody, especially! You can put "visitation as parties agree" since neither of you seem positive about if/when he's coming to join you. I just know that even when amicable, things can turn bad quickly, so get it in writing while he's still agreeable!!!!! That's my best advice. Don't worry that getting it in writing will turn him away. If he wants to be a father, it won't make any difference. And even if it's in writing, you guys could still try things out later on....but you must protect you and your child, first and foremost.
It sounds like you have already made up your mind and you are just looking for some support. I support you!
I think it is very important to do what you feel in your heart, and it seems like you need lot more from a husband than your husband is willing to offer. It's great that you can recognize it and have the courage to do something about it. Good luck with your move! I'm in FL too, SW FL to be exact.