Alcohol-related anxiety - advice appreciated

I apologise in advance for the length of this post - this is quite a long story.

My mother was an alcoholic. She died just before I turned nine; although I was quite young, I remember quite a lot of the horrible events that occurred when I was a child (I'm now 25). My mother was never violent towards me, but I was quite badly neglected when she was drinking, and she was extremely violent towards my father. My parents divorced when I was six, and I moved away with my father. He remarried when I was seven, to a woman I have never particularly liked. When I was about 15, my father also started drinking a lot. Where my mother had been dependent on alcohol, however, my father was the CEO of a business and only drank heavily at social occasions, like business dinners or receptions. Thankfully, he stopped drinking altogether about four years ago, but his drinking brought back a lot of unpleasant memories from my childhood.

All these different negative experiences drove me to depression, anxiety and self-harm. I managed to keep them relatively under control at first, and got into a relationship when I was 16. My boyfriend's family all liked a drink, and at first, this was fine. I do drink alcohol myself, socially, and would go along to family gatherings and so on. One night, however, when I was 17, my boyfriend went out to the pub with an older friend, and got paraletically drunk. I was staying the night at the flat he shared with his mother - when he hadn't arrived home by midnight, I phoned him and received a barrage of abuse. This left me quite shaken, but when he came home, things turned into a full-blown argument, and at one point, he raised his hand as if to hit me. He didn't actually touch me, but it deeply affected me. I sank back into a deep depression and began harming myself again. From then on, every time he said he was going out for a drink, I would start shaking, my stomach would have butterflies, and I could feel the panic rising. I would do my very best to talk him out of it in whatever way possible.
Shortly after the incident when he got very drunk, I finally sought help from a GP. I had 14 months of psychotherapy, which seemed to help with both the depression and anxiety. Unfortunately this had to be cut short as I had turned 18 (so would have to start paying for the therapy - £50 for 50 minutes, which neither my family or I would be able to afford) and because I was moving to university. I was referred to the University mental health team, but they were absolutely awful, and after the initial two assessments I didn't go back.

I split up with that boyfriend when I was 18, three months after moving to university. Since then, I have had two relationships lasting at least a couple of years each, and began a relationship with my current boyfriend four months ago. In all three relationships, there seems to be some kind of pattern: everything is fine for the first few months, but then they go out without me to socialise, somewhere involving alcohol, and I completely freak out. I really thought I had learned to control this anxiety - I was on Citalopram for around three years, and came off it recently, and took a course of Cognitive Behavioural Therapy to try and deal with precisely this problem a couple of years ago - but last night, the anxiety hit me again, for the first time in this relationship. My boyfriend and I just got back from a week's holiday where we drank alcohol together and everything was fine, but as soon as he messaged me to say he'd smashed a glass as he was a bit drunk, it hit me like a ton of bricks. The same, familiar anxious feelings: shaking, sweating, butterflies in my stomach, utter panic. My default response is to get angry and refuse to speak to my boyfriend for the rest of the night, perhaps trying to make them feel bad for making me feel awful. None of it was malicious, though, and neither he nor I expected the reaction that I had.

It is very apparent that I need some kind of help or advice in terms of coping strategies, or perhaps more professional help to work through these feelings. I can't quite describe what it is that makes me so anxious, particularly as I'm not there. Part of me thinks it's the fear that they have lost control of themselves as they are not sober, and I know that if I try and picture what they might look or sound like - bloodshot eyes, slurred speech, not being able to stand upright - it makes things a lot worse. Usually it's all grossly exaggerated in my head - even if they go out for just one drink, I have the same reaction. I have tried some basic strategies like relaxation and breathing techniques, but I can never seem to pull myself away from the intense feelings of anxiety. All I want to do in that situation is go to sleep and try and forget about it. It's like I can't stay awake/conscious while I know they're still out drinking.

I am so worried that this is going to cause all sorts of problems in my relationship. My boyfriend is very understanding - he says we will get through this together, and that he'll be there for me - but my anxiety around boyfriends out drinking has caused so many arguments and awkward situations in the past. It's almost cost me at least one relationship. I don't know what to do, in the short term at least. I don't want my boyfriend to feel like he can't go out with his friends because of me, and I don't want to find myself trying to talk him out of not going out because of my anxiety, that's just not fair on him. I've wondered if he should just not tell me when he's going out, and not message me, but we talk so often that I think that will make me worry more, if I don't hear anything from him. I feel like I'm in a total Catch 22 and don't know how to cope with any of this. I really thought I had got over the worst of this anxiety, but it's come back to bite me in a big way and is making me extremely upset.

If anyone has any advice to share, or strategies they think might help with this kind of anxiety, I would be very grateful. Thank you for taking the time to read all this.