This time when he pulled every mob in sight, I was unable to heal him enough and he died and the group wiped.

I was taking the shortcut back when the tank asked in group chat if I was dual boxing. He then asked the group to boot the healer. I asked him how fast he thought I could heal and got no response. He proceeded to pull an entire room again before I could even buff the group.

I decided at this point that I would just do something else and left the group. I had been playing a tank before starting this conjurer and have never left a duty group before, but it was late, I was tired, and just didn't feel like continuing in this situation. I mean, I play to relax and have fun.