CPE formal letter

Hi everyone!
I've just received the news that the company where I work is willing to pay for my CPE examination. I'm totally at a loss since I have nobody to give me a hand with my writings. Could someone be so kind to help me, please? I would be so grateful!!! Format, register, and style are my main concerns. Thank you so much in advance!!!

The instructions were the following:

You have read an article in an international magazine on the topic of friendship. The magazine has asked readers to respond with their views. You decide to write a letter. In your letter you should briefly describe a special friendship that is important to you and assess the difficulties of maintaining friendships over time and in changing circumstances. Write your letter. (280-320 words)

Well, my attempt is this:

Letter to the editor

Dear Sir/Madam,

I am writing to you in response to the article published in your last Sunday’s edition about friendship. Since readers were invited to share their experiences and opinions, I thought I could have a say.

My friendship with Cynthia started 22 years ago when both of us were little girls. Our parents started going out together thanks to a mutual friend. At first we didn’t like each other much. In fact, we didn’t have any interests in common, so we just had to put up with each other while we waited for our parents to catch up with their lives and decide to come back home. However, after some months of such a routine, we got to know one other better and finally we discovered that our differences could be a complement instead of a drawback in our relationship, and in no time we became the closest friends.

Time went by, which made things hard: work, studies and responsibilities started to weigh more than social life, and without even noticing it, a day came when we felt each other too far and distant. Moreover, we were practically strangers who once in a while talked on the phone and updated their news, until a misfortune got us back together. And it was then that we saw clearly how much we had been missing.

Nowadays we are trying to get our treasure back by giving it the importance it deserves. We got to understand that there are more important things in life which may not fill our pockets but our souls, and one of such things is friendship.

A true friendship will remain strong, and when the circumstances are appropriate, it will flourish again. It is just a matter of determination and will on both sides.

Thanks for letting me share my experience with you.

Yours faithfully,

Lucio The Duck.