Not trying to be rude at all, just telling you my opinion on it. I've seen so many moms be bitches to their ex's and plot all kinds of shit and then end up regretting it when they're in front of a judge.
They can't take your son away from you unless you're on drugs, alcohol, or you're a neglectful mother. In my opinion it's best to NOT play games and try your best to be civil. That is what the court wants to see. They want to see that you have your sons best interest at heart which means being the bigger person, and acting mature even if you don't want to. There's nothing wrong with gather negative information that you truly find could harm your son. But playing him doesn't sound like a good idea to me. If the court sees you acting like a real parent, they won't take your son away from you. It's very unlikely for the dad to get custody unless you have some major flaws he can use against u.
I'm playing my baby daddy after all the shit he did to me and I am willing to get any information I can to be sure they don't try to take my son away like they plan in doing.