How to write a letter to your friend apologizing?

Me Dear Friend,

Please take my friendly salute. I had got your invitation to attend your dinner party. Just at the time I got a letter from home that my grand-father was seriously ill. I got, hurry to go home from my uncle’s house. I was in much a hurry that I failed to drop a card to you to this effect. So, I could not attend the function at your place. I hope, you will not mind my absence and will excuse me for this.

Please convey my best regards to your parents and my blessings to younger ones.

Yours Loving Friend

Your Name

Image Source: theinspirationroom.com/daily/interactive/2013/3/easter_bunny_my_apology.jpg