Suspended for gross misconduct

I was suspended for gross misconduct yesterday on full pay. I showed up to a written warning disciplinary meeting drunk. And now I have another disciplinary meeting for gross misconduct for being drunk in the previous disciplinary.
Let me explain why I showed up drunk, which was a huge mistake. I have autism and anxiety issues and take medication for it and the day of the disciplinary I had unexpectedly ran out of the medication which calms me down. In a panic I decided to drink a few glasses of wine as I was finding the whole thing very stressful. I got a little drunker than I intended to, I just wanted to relax. I should have been more careful. I have issues with alcohol dependency and tend to use alcohol as a way to cope with anxious situations and I really couldn't see how I was going to get through it without something to calm me down. They didn't tell me I could have a representative with me, and the meeting was with someone I'd never met before, it wasn't my manager. They know about my alcohol and anxiety problems, btw. And they know I'm on medication for it. They also know I have autism.

I'm worried sick and extremely remorseful. I've worked there for over 3 years and I'm very good at my job, and I really enjoy it. What are the chances of me getting fired? it's going to be near impossible to get another job with this on my file.
When I have the actual meeting for the hearing I will be telling them that I have quit drinking and will be starting on anti-depressants. Would this help my defence?

Thanks