Friendly advice 

I know it's tough. He can certainly be infuriating I know. It might be a good idea to just 'drop-out' for a bit and let other editors deal with him. Choose one of your favourite articles that he doesn't edit and work on that for a while. I know you don't intend this, but the 'discussions' you 2 have often escalate to such an extent that the issues have been sidetracked to your personalities; this damages the work and spoils things for other editors with really good ideas and things to say.