I'm not inviting my son after he chose to be with his mother
I'm saddened to hear this. Why did your son choose to be with his mother instead of you?
I can't pay for his college education
It's understandable that you feel slighted by your son choosing to live with his mother. However, you should not neglect your son because of this, instead you should invite him and explain your feelings to him. Excluding your son from your life will only make your relationship more strained.
You are wrong, I'm not neglecting him.
You've said it yourself, you will not invite him and that is a form of neglect if you are his parent and he is your son. Taking care of your children and making sure they develop is something that a parent must do and if you don't do it, you're neglecting your child and I hope you realize this so that you can change your decision of not inviting him to your event.