Dear dad.
I know you are mad at me because I lied to you today.I am very sorry about the lying.I was too confused and didn't know what to say when you asked me whether I broke your cup or not.It was me.I broke your cup by an accident.I was running in the living room and fell over.I swept your cup from the coffee table and it was broken.I know you are not mad about the cup,you are mad about me lying to you.I should have told you the truth but I am afraid you are going to punish me.I will not do this again.Please forgive me.
Yours,
Son