Eastbound ... I went through something very similar. I had a relationship not go the direction I thought it should go and was devastated. More than that ... I was left without direction or motivation.
I second the recommendation to see someone about your depression. You've been through a traumatic event and it's okay to get help. Same with the substance abuse. You know deep down that you can't make progress until you get this under control.
Ultimately, I made progress when I found something bigger ... and outside of myself ... to which to devote my energy and passion. I had to get out of my head and out of my own way. It makes sense now, but it took me a long time to get to that point.
Thanks for posting.