Chin up mate! I know its hard ive been in a similar situation myself. I wanted to give up on everything, and i mean EVERYTHING.
I think id be looking for another job, but maybe in a totally different line of work? try to talk to different people, get a round a bit, find out whats available. do you know anyone who does something you wont mind giving a go?- speak to them, mention you want a new job, maybe even try and get involved a little bit.
I know its hard but you have to try not to let it bother you, if you do it will only get worse and like you already said youve gone back to bad ways due to it- do you really want to go there again?
dont let your current situation prevent you from moving forward, your CV may only show qualifications for your current line of work, but nows the time to change it. apply those skills to new roles.
If you wanna chat, just let me know.
Nat.