I know those feelings. I once relapsed after seven months. And that was gong to AA.
Don't ask me why I drank that time, I didn't know.
Just pick yourself up, learn from it and don't dwell on it and move forward.
You're not useless or hopeless. You're human and humans are fallible and make mistakes.
I've got almost seven years sober now and I was a bad drunk. It took me about seven years of trying to quit to get this far, so don't be too hard on yourself.
Best to you and sending good thoughts your way.