i am soory to call you after the working hours but I have an emergency.

i am afraid i have to postphone our meeting

四、Cancelling a meeting

以道歉为目的的：直接表达歉意

以拒绝为目的的：先肯定再表达拒绝

I'am afraid

I'm terriblely sorry

I can't be away from the office

if you don't mind,

in the meantime,if you'd like to

how about?