Cute letter

I received this cute letter from two of the graduating boys from my junior high.
If you can't read it, it says:
Dear Ms Audrey,
Thank you very much for teaching us English!!
We enjoyed your English class!!
Audrey, you're very kind and cute lady.
We love you very much! We are happy!!
Do you know the Japanese word "uha uha"?
Please ask N or F.
Our hearts always were broken in English class without Audrey-Sensei.
Never forget N and F.

(apparently "uha uha" is equivalent to "yay!")