I know its hard to hear but like the others have said, this is not about you helping him, He is the only one who can get clean. A four year heroin habit is not going to be broken in a few days ... he will most likely need some kind of program. The salvation army has a free program and there are other options. I agree with tbeit, I've allowed my son to detox here in my home twice and what he is describing does not sound like heroin detox at all ...
You really need to focus on yourself ... It's not like you can't help at all, you need to figure out HEALTHY boundaries for yourself. We are all different, no one can tell you exactly what you can and can't do. I've told my son this "As long as i feel you are seeking sobriety I will help you in ways that are healthy for you and healthy for ME" We haven't always agreed on what is those ways are but my boundaries are firm. Nar Anon is a great place with lots of great literature to help you figure out those boundaries. If you don't find help soon you will most likely find yourself as trapped and sick as he is .... just in a different realm. I think it's worse for us because at least the addict has the escape of being high and oblivious when they use .. for us each day becomes hell moment by moment waiting for the next catastrophe.