I completely understand how you feel. I don't live with my ABF but a few months ago I would always be round at his house to try to stop him from drinking. I thought that if I was jsut there, he wouldn't get drunk. This did work for a while but inevitably he became sneaky and would lie to me and cause arguments so he could 'go out for a walk' (to the store). My work suffered becasue I took lots of time off to ruch to his house if I thought he was drinking or about to drink. I was ill from worrying constantly about whether he was drinking or not.
I still worry and I still sometimes go round to his house when I think he is drinking, but I definitely make a lot more time for myself. This improvement might not sound like much, and I still don't go out to see friends much, but it really has improved how I feel. My advice is to start slowly and make little attempts to do things for yourself - maybe just things around the house to start with - a long bath or some exercise - then work up to going out for a short walk - then eventually going out for the evening. You already feel lonely, so you might as well feel lonely while trying to make yourself feel better too.