How would you handle a child father that didn’t want to be involved in anything in his life besides when he visits there?

We have been divorced since my son was 2, he’s now 10. His dad has more kids now and is remarried. His family never goes to anything of my sons. He isn’t involved at all unless he is there in the weekend. No school events, no dr appt, no sports and he doesn’t ask about it either 🤷‍♀️ if my son has something planned on the weekend he is supposed to be there, such as sports, I have to get him and bring him back so he can go or his dad wouldn’t bring him. But what’s weird is he makes sure to go to everything for his step son and other child. He doesn’t miss anything. My son is noticing and it hurts him. They will go on trips without him and go to NFL football games without him (on the weekend he is supposed to be there but lie and say they are sick so he doesn’t go). It’s so aggravating and it pushes me to want to say things but of course it wouldn’t matter. I hate that he has to go there with someone who doesn’t know their child in most of their life 😕