Dear friend Harry,
I cannot gather words as to how to begin and how to apologise for my mistake. I would start by saying that “I deeply value your friendship and I am heartily sorry for breaking your trust”. Looking back to that day, I have realised that it was inhuman of me to behave with you in that manner. You have always been a wonderful, helping, loving and a great friend, standing by my side in every rise and every bend. I should have talked to you and should have cleared the misunderstandings with you before behaving in such a rude manner. Harry, I am really sorry for such kind of actions and I do not want to spoil this friendship with you.
I was actually frustrated when I heard from our mutual friend, Jack, that you lied to me and I trusted him blindly. Without even confirming and clearing things from you, I started shouting at you and I feel horrible for all the things that I said. I am extremely sorry for my behaviour and I hope you will forgive me for the last time.
I deeply value the friendship that I have with you and I hate to think that I had hurt it because of my acts and behaviours.
Please forgive me!