[Your Name, & Address here]
[Recipient Name & address here]
It is really difficult to write this letter to you. I don’t know how to start, but I have to tell you about it.
At times, there are many things that we want to tell our friends about, but we are afraid that something might hurt the person and, I am in the same situation now.
I know it well that what I am going to say will be really hard for you to hear & accept, but it will definitely help you change & improve. And, believe me; if I were in your place, then I would happily want you to do the same for me.
[Person’s name], the truth is that [Describe here what you don’t like about your friend].
Now, I hope you will realize and accept the truth. If you are angry at me, I can understand it. But, I had to tell you this as only truth will improve you.
And, if you want to discuss it with me and have your say, please call me anytime.
You are a dear friend, and I only want to see good things in you.