Dear …

I just found out that I have made a huge mistake. I feel terrible about how unjustly I spoke to you, only to find out later that it was no fault of yours at all.

I am very sorry for how badly I treated you, __(Name)__. My actions were unwarranted and unjust. I think the only thing good about it is that I have learned a valuable lesson throughout this unpleasant ordeal. From now on, I will be conducting more thorough investigations before I go flying off the handle and wrongly accusing people.

Please accept my sincerest apology for the inexcusable way I behaved towards you. I genuinely regret it.

Sincerely,