Coursing adrenalin

I quit just now. There's a tinge of regret, no doubt.
My head of department admitted to me that comments in my appraisal related to my cancer and that he should have transferred me to the newly merged company at a higher level. So there's some concession there, but it's too little too late. I don't want to be a hard arse over this, but if I knew about someone else being treated as they've treated me, I'd be really pissed off.
The head of HR came to see me within about 5 minutes of me resigning, asking me to reconsider, so I'll spend tonight discussing with Helen and try to take as open a mind as possible.