They probably discharged you because you got drunk... i'm assuming as you're from England you will have been on an NHS ward rather than private. My experience of that is that there is very high demand for very few beds. They perhaps saw your drinking as a way of you not complying with treatment or failing to help yourself. I'm not meaning to sound harsh or accuse you of anything, I'm just saying how they might have seen it. But if you're still struggling, and it seems to me you are then perhaps it's worth speaking to your CPN or crisis team and seeing what they suggest. They might agree hospital is in your best interest, maybe with less leave so you don't have as much opportunity to get drunk.

Hope you're feeling much better soon!