You are really super! Please don't forget to write to me OK? I'll be waiting.
Remarks about the translation
"não deixe de me escrever" is a hard structure to translate into other languages, but the meaning is that. Don't stop doing something or don't forget to do it.
But 'but for' doesn't fit with the rest of the text. I reckon the intention was 'demais' and the spelling is wrong. I think the translation captures the intention of the original very well.