I am writing to apologize for the way I have acted recently. I know that I have been unkind and disrespectful to you, and I want to express my sincerest apologies for my behavior.
I understand that my actions have caused you pain and frustration, and I am deeply sorry for that. I take full responsibility for my actions and I understand that I have hurt you. I want to assure you that this will not happen again.
I want you to know that I value our relationship and I want to make it right. I know that I cannot undo the damage I have done, but I am willing to do whatever it takes to make it up to you and to rebuild the trust between us.
I understand that I have let you down and I am truly sorry. I hope that you can forgive me and that we can move forward. I am committed to being a better person and to making our relationship stronger.
Again, I am sorry for my actions and for the pain I have caused. I will do my best to make it up to you and to make sure that this never happens again.