Speaking from experience, having a baby can set everybody's sleep schedule out of whack. If he's that reliant on alcohol to regulate his sleep, he needs to get himself off it now, not later. Because Anvilhead is right, he's more likely to drink after the baby is born if alcohol is his goto fixer upper. If he finds it difficult to cope with life now, it's only going to get more challenging.
The fact that he drinks when you're asleep/away sets alarm bells in my head. The fact that he's defensive about alcohol consumption is another one.
my husband is kinder, more loving and affectionate when drunk.
Unfortunately, you need to be kind, loving, affectionate and ALERT to be a good husband and a father. Our son was especially colicky, it was hard enough to be alert (and we were sober) because he was up at all hours at the night. I can't even imagine trying to take care of him while drunk.
However, I suspect you already know this, which is why you're posting your doubts and suspicions on this board. Your mama bear instinct is already on alert.
Your gut is telling you something. Listen to it.