Smarie, I'll be honest. I scanned your post, but after the first paragraph I had one dominant thought that obliterated the rest: Who cares if he's addicted to you? It sounds like, that despite your protestations, you're addicted to HIM.
Think about it...how do you bring the relationship back down to earth and its obvious flaws when you are getting reinforcement of some kind of perfection of who you are.
I wouldn't make the effort to bring the relationship down to earth. Like FireSprite, this would set off so many alarm bells in my head I'd bail out as quickly as possible. And you yourself articulate the reasons why...
I simply feel overwhelmed by it and perhaps even burdened in a sense because there is a part of me that feels controlled by it.
What you describe isn't a relationship, it's a prison.
And here comes the 2x4.
Would you seriously want this man, this alcoholic cheater, to be the father of your children? A man who already has abandoned his own wife and child? Are you so desperate to tick off the boxes that you're willing to risk your own children's mental health and well-being to do that? You may say to us that you wouldn't seriously consider having him a father, but your actions are telling a completely different story. Every day you spend thinking about him and his problems is a day committed to fixing him up to be Fantasy Father that you want him to be. But the odds of actually achieving that are pretty low. And he isn't even divorced yet, right? He's got another family to do right by.
You look at your friends' social media feeds seething with jealousy over the families they have, but you stay stuck in your Cave of Him and You.
So many other members on this site were blindsided. Their partners were extremely crafty at hiding the issue. The truth unfortunately trickled out drip by drip. You have been extremely lucky. Your A has shown you who he actually is. Take that and run.