If what you've said is all true, and you've thoroughly gone over with your attorney all of the grievances and have enough data to back it up, and they have yet

If what you've said is all true, and you've thoroughly gone over with your attorney all of the grievances and have enough data to back it up, and they have yet to respond within a reasonable timeframe through a legal channel, then go for their jugular and take them out. Don't relent on these types of offenses, doubly so if they are a start-up. Without knowing too much about the founders, say this kind of activity goes unchecked, and continues rampant within their business despite still being successful. That could potentially send signals to departing entrepreneurs that this kind of behavior is OK and that they could very well get away with it as well. Go for the kill.