Translation of frialdad in Spanish-English

Let's not forget how we started. We were writing each other very long messages and today we are both much more fluent in both languages. No book could have brought us that far. Cheers.
I think I have told you that I won't charge you for this kind of help. I looked at the sentences and I found them a little too long. They were good, but I understand why it took you so long and I think the point is too keep the shorter.
For my future job it is important to speak English and to be able to write it. What are you studying at university? If you are not very busy, I'd be very happy if you write me.