I've gone through patches like that with my dh. Right now we are going through a toughie. And there are times I wonder if I ever loved him. Like yours, he is a good dad and I get on well with his family. But I also know that these bad patches eventually heal over. We do talk together and we are good friends, which makes all the difference.
My feeling is that he is as unhappy as you are. So here you have 2 very unhappy people, neither of which is willing, or able, to make the first move to resolving things. Perhaps he has the same fears as you about leaving. You need to talk to him, ask him what he wants to happen. But you need to be non-confrontational. If you have both made a mistake, then you should set each other free to pursue happier lives. But you cannot have been drunk all through your courting and marriage, you must have had sober points when you had the choice to call it off, but you didn't. So something inside you must have been attracted to him. Perhaps that attraction can be rediscovered?
You say he is grumpy and doesn't speak to you. Perhaps that's how he sees it too? I'm just trying to look at both points for you. If there is something there worth saving, then I would go all out to find it personally. Leaving him now seems a bit rash and premature.
How long have you been married? Have you had counselling? How often do you get to go out as a couple? You say you are free to go out on your own, so presumably your husband acts as babysitter then, do you return the favour to him? Have you suggested a night out on your own?
Please look at the wider picture before contemplating leaving someone, because leaving him has many implications and involves many people. Loving someone is often bloody hard work, you're not in love all the time, you can have periods of 'falling out of love', but believe me, you can fight back and begin to love again, and so can he, you need to give each other a chance.