estranged son will be 33 on the 28th

I welcome advice, suggestions on this so PLEASE whatever anyone thinks on the topic please do.

My son who I have had no contact in years will turn 33 soon. Every year I go back and forth until I am nearly crazy trying to make the same damn decision do I or don't I send a freaking damn birthday card. A trusted therapist who knows of my estrangement says "send the card your still a mom" WELL I do not feel like a freaking mom anymore.

The dilemma is I will regret it if I do not because this little voice creeps into my mind and dashes my confidence and says "but your his mom remember?" which is true I just don't truly feel it if you know what I mean.

Do I just do it because it's a fact I am his mother and it's appropriate. I am afraid if I ignore his birthday which I have not done as of yet IT WILL GIVE HIM JUSTIFICATION to continue estrangement with impunity.