But Zake, can still create expensive and time-consuming lawsuit depends on jurisdiction. He can also create PR/Reputation problems that could be hard to mitigat

But Zake, can still create expensive and time-consuming lawsuit depends on jurisdiction. He can also create PR/Reputation problems that could be hard to mitigate. The right approach would be a combination of law in your country and your knowledge of Zake character. I would recommend consulting with a startup lawyer and maybe try to find a win-win situation for both of you where he can exit with face, and you can afford it.