Hey Alex,
I hope you are doing well. I am sorry to say that I could not go to your party this Saturday afternoon. I know you have been planning this important party for a long time coming, but I have an unexpected business meeting with my boss and my sales associates. It is such an important meeting so I could not miss it. I hope you can understand my situation. Could we plan to meet another day? How about we get together for dinner Saturday next weekend instead? Perhaps we could meet at Thuan Kieu restaurant and talk about your party I missed or anything else on your mind? I hope you would accept my invitation as a token for my apology for missing your party and it will be my honour to treat you. Again, I hope you have a great party and my sincerest apologies.
Take care of yourself and get back to me when you can.
Jerry