考虑到现在你与她的关系只是私人关系,我会用私人电话/电邮告别。没有必要让办公室的人都知道。
一般来说,她的老板和你的老板之间的关系,或大老板和他老婆的关系对你没影响,除非你所在的公司只有很少的人,大家每天没事干翻闲话。
如果只能电邮,我会这样写:
I just heard you are leaving the company, it is sad to see you go.
I've worked with you for ()years, and I learned a lot, (具体写三条她对你的帮助).
Thank you very much for all the help and good luck to you.
这种写法,公开或私下都挑不出错来,但对一个被开除的人,是很大的鼓励。