I am asuming you are a teenager, I think writing the letter was a very mature thing to do , and I am sure they appreciated it, believe me it is a tough time for both teenagers and parents, we just don't seem to understand each other.

Don't worry too much I am sure although today you felt grumpy and they said they did not think you really mean't it, they are probably just testing you, and hoping you will show them again how much you meant what you said.

CHEER UP, life is good and your parents LOVE you too ya know.