His behaviour is controlling because in a healthy relationship if a person doesn't like their partner's friend, they just stay away from the friend. They don't make you feel bad about seeing them, they don't "worry" about you, because they trust you to look after yourself. I mean, of course everyone worries about their partner occasionally, but just for a night out? Nah, that one is odd. I mean, unless you can clarify that this friend is genuinely bad news and she's got you into some scrapes before, or something like that? Does she get you to do drugs you have otherwise stopped taking, does she involve you in illegal activity, is she a bit of a "frenemy" who is actually out to screw you over? Those are the kinds of situation where I can see that his level of disapproval in relation to her would be "helpful".
I would be really wary - it's very normal at this stage when you're both pretty carefree and independent to think oh he's just being really caring, how cute, or he's a bit insecure, or he's trying to look out for me or be helpful, etc. But it's not really that, if you look at what he's actually saying he's saying that he doesn't trust your judgement (of this friend) and he doesn't trust you to be able to look after yourself, around a friend or not. Because it is honestly okay for you to get drunk. If you are falling around pissing yourself and unable to walk then he would be right to be concerned, but that's not the impression that I got and hence I don't think this is a normal level of concern. That is why it is controlling.
I believe you that he is a million miles away from hitting you but the truth is that controlling behaviour is one step on the bottom of a very long ladder which can lead to hitting. It doesn't always, but the connection is there and that is why that poster asked you.
There have been threads done in the past about why men seem to suddenly change when a baby is born - it is marked and well known, that abuse often begins or escalates in pregnancy. When you read the threads you see that there were always, no exceptions, always little signs beforehand, and your story about how exactly he shows his disapproval of this friend (which would be fine on its own, again, it's how he reacts to it and expects you to change your behaviour because of his dislike.) - this is one of those signs.
I can try and find a link to one of the threads if you like. It'll be reassuring or eye opening, either way!