Realistically, your marriage is over.
It's not one of equals - you are just the boring nag distracting from his one true love, his mistress that he adores, craves and is constantly looking for a chance to get balls deep into. You'll be blamed for stressing him, for being horrible to him, for not appreciating him. He won't be pissed whilst in charge of the baby, he just 'nodded off for a second' because he 'does everything for you, you just sit there doing nothing but criticise'.
You will never be able to trust him with the baby, not to change a nappy, not to put to bed, not to cuddle on the sofa whilst you have a shower, as there's a good chance he'll be drinking whilst you're in there or if you go out, he'll fall asleep/pass out whilst holding the baby, massively increasing the risk of suffocation or dropping on the floor or you'll be wondering whether he's fallen over shitfaced on top of the baby or down the stairs. You could find alcohol stashed behind the car seat, under the cot, beneath the nappy sacks and each time he's up with the baby if he wakes up rather than snores his way through all of it, there's a chance he'll be knocking back some more.
This assumes that he'll even make it to the hospital for the birth, whether he'll be sober enough to drive you, whether you'll see him after he 'pops home to get a change of clothes' or 'I'll go and get you the formula and nappies'.
He'll then teach your child to associate the smell of alcohol with home, miss drop offs and pickups, not turn up to nativity plays or be pissed in the school playground, telling you that they're making it up, they're all wankers and jealous bitches who hate you when social services is contacted. There will likely be massive rows where he disappears during school holidays, just before Christmas and probably on the baby's birthday before rolling in shitfaced demanding that he gets to see his child.
Oh, and he'll say you're fat and let yourself go after the baby's born. Only way to shut you up about his drinking, you see. And then if your baby gets attached to him, he'll leave them decades earlier through being absent when physically there (as his mind is on his mistress), through being absent when he's supposed to be there (as he's off getting pissed) and through turning luminous yellow and dying, possibly in a torrent of blood as varices in his stomach rupture.
Dump him now, divorce him asap and you'll reduce the harm to your baby. Not to nothing, but less than it'll be if you continue to tolerate this.