Well here is my 2 cents for what it is worth.
Why do you need to know if it is heroin? Will that be the deciding factor? First of all he is seeing someone, you establised that.
Second, you found an arsenal of drugs which is like another mistress and he is spending time and money on that. Then you find what probably is heroin or something equally dangerous and illegal and now you decide to confront him with facts.
He has put you in the position of going down with him. Who cares what you found. You found it, it will probably kill him, destroy brain cells he will never get back and spiral his life down to hell.
So what is there to confont? Run, don't walk away as fast as you can. Rid yourself of him ASAP, don't be an enabler and help him with rent and bills by staying with him.
It is your choice but, think about it. The sooner the better. Just say bye bye and feel bad for a week or so and get on with your life. While you still can think clearly!
Good Luck!
