[iquitmyphd]

(Sort of disclaimer, this may or may not be terrible advice from a legal perspective, IANAL)

So first off all, get someone to talk this through. Ideally someone who can give you an honest opinion, but any second opinion is better than none.

And second, after you decided to use the nuclear option, shelf it as a plan B. The nice thing is, almost everything is better than that. So you can plan with a lot more freedom, and you can play with a lot of risk. If it does not work out, then you just push the button and go nuclear. In your case, when you decided that there is only one of you left when the dust has settled, then you don't need to worry how you can work together in the future. One way to exploit this, you can be brutally honest. Perhaps you find a common basis again, or you go to your board.