[Porsche-O-Phile]

Methinks you've painted yourself into a corner and you're now confronted with having to do something borderline unethical, possibly illegal (not disclosing communications that may very well be company property despite being specifically asked to by an employer) or be put in a "hostile work environment" with an employer that knows you despise them by disclosing the messages that show you can't stand it there.

If you disclose all but the "unsavory" messages and it goes to court, you can bet the opposing counsel will point out the discrepancy between what you provide and the sub received (never mind it's not directly relevant to the matter at hand) to attempt to discredit your side. At that point if it's a "surprise" to your company in the courtroom you can bet they'll be furious with you and retribution will be right on its heels - particularly if this company (as you say) is so giddy about suing people and cherishes its lawsuit track record.

You may seriously want to consider talking to legal counsel and / or resigning. If all those messages ARE company property and you get subpoenaed to hand over "all correspondence" with the sub (as you probably will be if you refuse on your own), I'd think you need to or else it could get a lot more serious than simply pissing off an employer and possibly getting fired (obstruction of justice?)

All-in-all dumb move.