Should I call cps on my ex?
That's not good. Why do you want to call CPS?
Because I felt like it. I can do that.
Is there any reason you think your ex might be harming children? If not, calling CPS on them would be wrong.
I cheated on my ex and the kid told him and I want to get back at them.
But you were in the wrong so you should stop trying to get your ex into trouble just because you are angry you got caught. It would be better for you to just forget it and leave them alone.