There is no way I would date an ex herion addict. I would run from this. He has to straighten out his life for him, by him, and through him. His leaning on you is just another dependence. You should examine why you would want to hitch your wagon to this star. Is this the first time you have been involved with an addictive person? I would wait at least 5 years before entering a relationship like this because
a. He did not seek treatment on his own
b. He does not have a job.
c. He does not have an apartment.
He will most likely want to skip treatment, move in with you, drive your car, and how would you be albe to get rid of him when and if things go wrong?
I'm sorry if I sound harsh but this seems like a no brainer to me, I just wish for you to avoid the road ahead.
Good Luck.