what to do?

someone i work with wronged me two weeks ago. like, in a serious way.
now they have sent one of those 'gee, i haven't seen you around
lately' emails. my contract is ending in a month at this place, and i
am not renewing; i am basically quitting, though if money gets tight
enough, i will have no choice but to go back.

...so how should i reply to this email?

sigh.