How do I get over it?

How do I get over continuously watching my daughter’s father choose to completely neglect our child but take care of his other child? He completely denied her and it took almost 3 years for me to put him on child support. He paid consistently for a year and now nothing. He sees my child maybe twice a year. I feel angry and jealous because now I found out he has another child on the way with the same female. How can he completely detached from our child? Not there during the pregnancy or anything but be there for these ones from the beginning but still treat my daughter like she’s nothing? Granted we’re not in a relationship but that should have no affect on the relationship with our child. How do I get over this? How can I not care?