vossy, I cannot recall your entire situation, but focusing on the communication issue at hand, I would say definitely NC. It is not rude, and he will not see it that way. He will see it as you having had enough, not 'oh wow, why is she being rude to me?' I would not even send him anything for his bday, or at least as of today, not be planning it. Why build his bday up in your mind today and spend the next 8 weeks dwelling on it? Not a good recipe for detaching. If you happen to remember his bday, and feel like it, yea, a simple text or email 'happy bday' and that is it.
Unfortunately when you are NC and have no reason (like kids) to force contact, you worry about never having contact again. I get it. But never say never because as Lisa said, you can always contact him in the future. However, your real fear I believe is NC not working at saving your relationship. Well, I will tell you that NC will NOT save your R by itself. NC is the first step. What NC does is it allows your WAS to understand what life is like without you. Believe me, you are not the only one thinking about the long history you have had. He will be thinking of it as well. He will have doubts. Like this wedding he is going to. Even the hardest heart will have memories of their own wedding when attending one. He may even get mushy/emotional and reach out. And I would reject it. A fleeting emotion is not enough to begin to rebuild a relationship. Let him stew in the emotions alone. Let him go through the emotions of the memories you two had. Because at that moment, he will be thinking of the positives. Jumping in yourself 'may' provide him the temporary emotional support he is looking for, but it also 'may' introduce negative feelings/memories. I wish I could explain what I am trying to say a little better.
I am sorry I cannot recall your entire situation or maybe I would be able to offer a little more.
Best of luck to you!
Me: 42 W: 32 Married 7 years together 8.5 S1: 7 S2:7 Bomb #1: 09-16-13 Recon #1: 11/13 A discovered 04-03-2014 W filed D 05-19-14 but never served me I filed D 12-02-2014 S 05-31-14 Divorced 5-19-16