I've kind of made it a general rule in my life not to get caught up in this type of thing. If people want to be in your life, then they'll make an effort to be in your life, not flake 15 times. That's an absolute joke. Sure, things come up now and then, but not 15 times. Either he's extremely insecure and afraid to actually meet in real life, in which case you should just find someone else, or he's just playing with you, which would also merit you moving on. Don't put any more effort into this, let him come to you - because he will if that's really what he wants.
We are really good at reading people, though our paranoia can make us a little bit hypersensitive. However, we pick up on deviations from prior behavior very easily and can sense abandonment, real or imagined, from a mile away. When texts become one word replies or far and few between; when suddenly someone doesn't want to hang out with you as often; when someone starts to flake or they don't initiate anything anymore - all of these types of situations can elicit the feeling of abandonment. But, when this type of behavior becomes routine and forms a pattern, such as cancelling 15 times, then it's obvious this person has little interest in having you in their life or making an effort to be in yours. Life is too damn short to waste on people like this.
I know you said you can't leave him, but the reality is you never had him. You've never met, he's never been in your life, and you're attached to the idea of this great person who treats you like shit and doesn't respect your enough to make an effort to even meet you. So please, don't waste your time with him. Believe me, I get it - if you're like me, there as so few people in your life that losing someone like this means being alone with having no one to talk to. We crave that connection with someone. Anyone. But, this isn't it.
And please don't overdose. Not over something like this especially. I once took 22 Trazadone and it was hell. I know that you said you've done this before, but you wouldn't be posting this if you really wanted to do this. So fight that instinct! You're worth it. Good luck!