We apologize for the delay in answering your letter.

来信收悉，迟复为歉。

《牛津词典》

I wrote this letter not just to apologize but also to let everyone know that we Filipinos are not all like Mendoza.

我写这封信的目的不仅仅是为了道歉，同时也是想让每个人都知道，我们菲律宾人不都像门多萨那样。

youdao

I've written him a letter to apologize and hope he'll forgive me.

我已经给他写了一封信，向他道歉，希望他能原谅我。

youdao