I did not beat him yet, but I'm on it ... so I think I'll share my thoughts as a basis for discussion! :)
I think you need to prep for a long fight - so here are my build and Item thoughts:
Kiting, dodging, regging while slowly draining Diablo is key.
Your stats seem nice, especially DPS - what's your build / Life Regen? You're using Glass Cannon I guess?!
I am at 40k dps (with ~2.5 attack speed), 40k life, 400+ resists, 1500Life/Sec (fully buffed).
My general build: http://eu.battle.net/d3/en/calculator/wizard#bXlRSO!aXf!baZbZY
The Idea is to cast Blizzard + Hydra and run around Diablo, obviously dodge his fire attacks. Fire Piercing Orbs at his direction, aiming from minimap while you don't have to dodge. Phase 1 + 3 you can hide behind these big rocks, don't hesitate to use Pots + Pools (they will respawn) if you get hit. Use diamond skin if a hit is inevitable.
Phase 2 is the real problem - only engage if at full life, run away the rest of the time and wait for CDs / regeneration. With 1.5k Life / Sec you need to run around for 20 Seconds without being hit to recover from low life! :)
I didn't have time yet to get enough tries done, but I got fairly deep into Phase 2 - but died twice due to lag.
As my gear gets better I might swap Force Weapon for Teleport/Frost Nova for even more survivability. But that's ~10-15k DPS, which is too much yet.
A question aside ... does Diablo have an enrage of any sort? Didn't notice anything yet although my fights seem ridiculously long.