Hi there Cali,
I'm really sorry for the toll this has taken on you, for everything you're going thru. I dated one guy when I was 21, he was 32 and he was a crack addict (lasted 3 months, it was an eternity!). Then around 2004 or 05 I went thru a breakup with a guy I lived with (who was really cool, smoked some weed, but not an "addict", no other drugs or drinking)... anyway I rebounded with a raging abusive alcoholic. It went on for 3 years. Be happy that this ended!
Early in this thread you said something like "if he doesn't reply to my texts I'm going to sit on his doorstep." Please don't ever do that. I know how that thought feels because I have thought it before. Have you considered really being single, just not looking or trying? I realized after really being single, like for more than a few months, that I was a serial dater and my standards were getting lower and lower. I was codependent too, obsessed, put up with crazy abuse... and I have some friends now that I put up with too much from that remind me, oh yeah, I fall for this.
Don't confuse pity with love, men are not stray cats! Feel better, this guy is obviously too much already- he's not even talking to you and you're upset, it is only the TIP of the iceberg. STAY AWAY- he's probably going to contact you if he thinks you're gone for good, stay gone, they pull this crap- STAY AWAY