[Address]
[Date]
Dear friend,
I hope this letter finds you in the best of health. I met your mother yesterday and she asked me to write this letter to you.
Your mom told me that you have been caught cheating in one of your tests. I understand your situation but I will advise you to not do it next time. You should understand that the aim of studies is not to get good marks but to become an intelligent person. I am telling you this because you are like a younger sister to me.
Visit me at my home so that we can talk about this more. Take care.
With love,
[Name]