Apology letter about for not attending to the party

Dear my friend Tom: I am writing to apologize for not attending to your birthday party celebrated on 24 of June. I hope you and your family are superb well. I received your invitation card the day before yesterday. At first, a number of thanks for inviting me to your birthday celebration. On the contrary I am deeply sorry to that I can not attend it although I had promised that I would attend it. In the light of the fact that on that day my father had an essential meeting and my mother also had to go to my grandmother till late in the evening. Consequently, I had to stay at home alone. In addition, I had numerous work to do on my own. Therefore, I could not go to your birthday party. I am surely you must have a nice time with your friends and relatives. Please do not be angry, I hope you will understand my problem. Once again I sincerely apologize for not attending to your party. I will surely meet with you when I have spare time. With lots of love I am closing this letter. Yours faithfully, John Brown.