Ask HN: SAFE and vesting: how do you value the company when a cofounder leaves?

Help!

I'm a CTO and cofounder of a company that I want to leave because of a massive fallout with my cofounder and CEO.

We raised a seed round using SAFE convertibles notes at a 8 to 10M value cap. I've vested half my shares in the company, HOWEVER, under our shareholder agreement the company has the right to repurchase my vested shares when I leave, at "market price" (yes I realize it was a HUGE mistake).

How do I go about valuing my shares? The money we raised doesn't automatically value the company, so I'm at a loss how to proceed and get some value out of the 2+ years I've built this company.

Please help!