Should I let it go?

Hiiii guys, so my dad claims he paid all my child support but I or my mom has ever seen a dime of it. He claims that I need to figure out why we never received it. I’m now 23 and know it’s petty and childish but it kind of really annoys me cause he’s been with this woman who buys him whatever he wants and they constantly take vacations and now he’s rubbing it in my face that they are going to Europe. Which why does this man who never supported his family get all these nice things now?? Is there a way I can go about actually figuring out if he paid child support or not? I honestly don’t believe he did because he has barely worked since my parents split up. He went to living off my grandparents to living off his girlfriend now. I’m expecting in May and know I should probably let it all go so he can have a good relationship with my son but he still does really slimy things to my brothers and I. Any suggestions? Even if it is telling me to let it go.