Get sole custody of your son; he should be nowhere near that narcissistic, sociopathic ****. Also sue her for child support. You're both better off without her. I'm so sorry you're going through this, OP.

That's a great idea. Judges always need a few good laughs. Once you become a laughingstock in the court's eyes, the pity can really work for you.

Bad news: divorces don't work that way in real life, just in fiction. If anyone cares about the fact that she prefers sex with her lover to sex with you-- which is unlikely-- and if it's actually relevant to the divorce proceedings-- which is even more unlikely -- your evidence will just be documented and summarized. There's no scenario where you get to shock the courtroom by reading her statements aloud. Now, the fact that she calls her son names may very well matter during the custody process, which isn't the same thing as the divorce process; but even then, they aren't interested in creating drama or giving you your moment of righteous indignation. They'll again just document and summarize that fact. Also, if that's the only context in which you can prove she called him names, I think it's probable that she'll just say that she didn't mean it, and that she was lying to her lover because she didn't want him to believe he was breaking up a happy family. That argument could be used for the bits about thinking of him while having sex with you, too; and it's honestly not that bad of a defense, as adulterers frequently do put down their spouses to their lovers by lying, for all sorts of reasons. Nonetheless, good luck, and I hope you get a fair settlement and a favorable custody plan.

At least you have the proof of adultery. Hopefully how crazy she is will allow you to get full custody of your son.