I am writing this letter to express my sincere apology for causing you emotional pain. I know that I have hurt you and I deeply regret my actions.
I understand that what I did was wrong and I take full responsibility for my actions. I should have been more mindful of your feelings and I am sorry for not being more considerate. I know that it was wrong of me to act in such a way and I regret it immensely.
I never intended to cause you any pain or hurt your feelings. I understand that my behavior was inappropriate and I apologize for it. I am truly sorry for the pain I have caused you and I want you to know that I am deeply sorry.
I want you to know that I value our friendship and I will do whatever it takes to make things right between us. I promise to be more mindful of your feelings in the future and I will do my best to ensure that I don't cause you any more pain.
I hope that you can find it in your heart to forgive me for my mistake and I promise that I will do my best to make it up to you.
Once again, I am very sorry and I hope that you can find it in your heart to forgive me.