I had the same experience my first few years out of college. Had a long relationship end, started drinking, went through several jobs and within three years found myself alone, severely depressed and an alcoholic. I contemplated suicide frequently, but held out hope my life would change if I could just get to tomorrow. My life started feeling like the movie "Groundhog Day".

Eventually things did change, and my 30's have been a whirlwind of happiness, sobriety and a GF who loves me unconditionally for me. Like you said, if I knew this is where the black hole I fell into would lead to, I would've pushed harder to get sober, try harder to put myself back together sooner. But I'm here now and am grateful I held out and often think about this wonderful life I almost passed on.