Hey PP. I wanted to comment on the part of you that is hopeful that things aren't so bad and will get better, and that thinks that things have changed and might stay better, and that your partner doesn't want to be a bad guy. There is a really sad thing here, which is that maybe a part of your relationship may be based a bit on a fantasy, and on you turning a blind eye to things you know are really very problematic. Maybe you feel a bit more badly about yourself than you let on: maybe the feeling of 'boredom' that you identify that you don't like when you are by yourself has a bit more of a flavour of anxiety, or loneliness, or depression, or feeling that you are not very likeable.
So maybe its not so hard to put up with your partner behaving like a bit of a wanker, or behaving a bit scarily, because it's a sort of compensation for not having those other feelings. This is really really really not OK.
In a healthy relationship partners are supportive and help each other with difficult feelings, help each other get therapy if that might help, encourage those kinds of personal development. Maybe you and your partner recognise those feelings of not fitting in in each other, and that makes it hard for you to think of leaving - you feel you'd be abandoning him. But his way of coping is to put his feelings of hurt and damage into you - to make you feel bad, to hurt you one way or another. Sure - mainly when he's had a drink - but he chooses to drink, perhaps so that he can let himself make you feel bad, so that he feels better.
What would happen if he doesn't drink? He's not got the resources to try other more healthy ways of managing his difficulties. And he's really not going to learn them by you asking him to. Its like asking him to learn a new language when everyone around him is speaking English. If he moved to another country, and no-one spoke English, he'd be motivated to, but there really isn't the need right now. You leaving probably wouldn't be enough of a motivation either. Maybe when he's much older, quite a few women have left him, he's less able to charm, that might be a point when he's ready to learn. But you've asked him a few times already and he's telling you he's not interested.
So really the big ask I'd say here is - how much will you care for your baby? Will you give your baby the safety and chance for happiness you can't yet give for yourself? Please do some reading 'Why Love Matters' by Sue Gerhardt. The early month and years of an infants life are so important, and they are so sensitive. And during pregnancy - stress hormones like cortisol in pregnancy cause lasting effects on babies and the adults they become. Please please give yourself some really simple clear concrete boundaries that you will leave and not tolerate, for your babies sake if not your own. Like: if he wakes me once (twice? but stick to it) when he comes in drunk. If he refuses to discuss the effects of his drinking. Try testing some of these now, so you can see what it will be like in the future. Lets presume he is on best behaviour now - can he keep it up when you push it? I say pushing but I really mean not accommodating his unacceptable behaviour. A baby will not be able to accommodate his wishes, and will get punished for it.
On a really optimistic note, if you do leave, and get in touch with Women's Aid, look into the freedom program, get some decent therapy to understand why you have been willing to tolerate this problems - after some hard work you may find that your life will expand and take off and you will probably be happier than you have ever been. I am friends with some women post domestic violence and they are not cowed and ashamed, they are wonderful assertive advocates for healthy relationships, their openness and sincerity wins them warmth and love. They frequently say they thought life would be so much worse after leaving but they are so much happier than they ever thought they could be.
I hope this is helpful for you.