That was the wise tomsteve that said that to you I believe!
Another saying that is used around here is no new contact = no new hurts and that's true.
Remember how you felt today when you finished talking to him, all you can expect is more of the same unless you stop it.
When I broke up with the narcissist I was dating, we stayed in contact for a few months (long distance).
I was discussing this with a trusted friend and they said to me, you have to stop talking to him. I said I know but that's hard (in a nutshell). So over a period of a few days, she kept saying this, I would tell her what he would say (perception check) and she would basically back up that he was an ass lol
So I did it. I wasn't crazy about hurting myself. So I said ok, I will try this for a day. That is something that can be undone. So I did, it was hard, we had been in contact a lot. The next day was probably harder, so I thought, ok just until noon - then 6 etc etc. I did that for a few weeks, I wasn't happy. I forced myself to try to function, I went out to see family, I went to the mall to walk around, just stuff like that.
Eventually, I got angry, I kind of forced myself to. What a jerk (and he was) wth was that. I was in a very low place emotionally when he arrived on the scene otherwise I never would have entertained the thought of talking to him, despite the fact that his fake charm was really good, he was a fake.
The anger propelled me away from sadness. Every time I thought of him I would not think kindly of him. That lasted for a few weeks, then it stopped, I was tired of it (frankly bored with it) and let it go. That was that.
Things like telling yourself Stop! when your mind starts to wander there. Like getting up and leaving a room when you start to ruminate, forcing yourself to go for a walk, even if it's only for 15 minutes. Driving to the nearest coffee shop and going in and buying yourself coffee (or whatever you like) even if you don't stay to drink it, take it home with you. You might even do that a couple of times in a day if it helps.
If you stop talking to him and think about what he has done, you may well get angry too. You can have compassion for him from afar. No one would wish addiction or mental illness on anyone, that does not mean that you need to sacrifice yourself and your sanity and your well being for him, if for no other reason than it is a complete waste of time. You have tried kindness, you have tried tough love, I assume you pretty much support him financially, you take care of him and try to reason with him and so is he in rehab with all that care and attention? No he is at the roach motel getting high.
Back to the 3 Cs - you didn't Cause it, can't Control it and can't Cure it.