Empty Mothers day. What was this about?

I left the 20 year marriage a few weeks ago. Things just was not working out. He wanted me back, but I refused to go back to the mental abuse I took for so long. As usual, someone has to be the villain in a relationship gone bad. I am that person. The kids who are 20+ (grown up) had decided .. pooor pooor pitiful daddy with nobody there to help him out.. decides to take his side. After years and years of verbal abuse they took from him. (dont understand that one) but whatever. The man who I married 20 plus years ago, who would never step foot out of the house to go anywhere with me or the kids all of a sudden decided he was making plans for him and them on Mothers day. Of all days. In my mind it was retaliation for me.. Am I right? So.. I sat and waited for my kids to call.. no ring. I did get a text stating happy mothers day from my daughter. How would you feel? I am quite upset at him for making plans for the three of them.... on mothers day. Any other day would have been fine.. but he chose that one. I am quite upset at all three of them to be honest. How would you handle this?