Pete,
Dust yourself off and get back in the ring!
I can relate to your experience. For me in the beginning of my using Alcohol and drugs helped me stay alive (as weird as that sounds), I was so depressed without it, I would have probably taken my own life. I was self medicating my life long depression. Of course pretty soon it stopped working and I was just going downhill.
For me, it took getting into intensive therapy, seeing a Doctor who specialized in Depression and Addiction. (Local universities usually have low to no cost resources available)
Going to at least one meeting a day,
Found a temporary sponsor to start working the 12 steps with.
Started exercising at least 20minutes a day,
Drinking lots of water,
Made a good attempt to try and get enough sleep.
Made sure to eat three meals a day at proper times.
Stopped hanging out with old "friends" if they wanted to get together I would suggest a Movie or a public Restaurant, I would not go back to there house or hang out in situations that would entice me to drink or use.
Volunteered, Tried to help others. Soup Kitchen, Hospital, etc. It got me out of my "head" (If Social Anxiety, is preventing you from Volunteering in person, you can always just Volunteer on line by helping people on this forum)
Wrote three items a day that I am grateful for.
I am proud to say that by following those specific items, I am a sober member of Society today with over 3 and 1/2 years of freedom from Alcohol and Drugs.
Of course everyone is different and may need more or less exercise or have a different "Recipe" for success. but I just wanted to share what helped me.
I wish you only the best, Please keep us posted!