I understand your falling in love in "letters". People in the 19th century did it all the time.
You are doing the right thing, D. (I can't bear to use your screen name. So little hope in it). You are doing right by not flying to be with him, not tracking down more information about his drug abuse, not trying to contact his family or friends. You are doing well in that regard. Hold strong.
That you stumbled upon this information (if it is accurate) about him would seem to be divine intervention, don't you think? God really does speak directly to us sometimes.
The only thing I can recommend you do for now is pray to God--however you see God--for protection, strength, healing for both you and for him (if he is indeed a real man with the story he presents thus far). You sound very broken, and in my experience, only God can help us recover and glue all our pieces back together.
If you decide to break contact with the man altogether, I just want to remind you that it will not be the great loss to him you might imagine, for the center of his world is oxycontin and/or heroin. For now it is giving him everything he wants.
Post here anytime you need. Welcome.
Bluejay