Ask HN: How to leave a startup that's asking you to give up your vested shares?

I'm leaving a startup I cofounded due to disagreements over strategy and cofounder conflict.

I worked on it for 24 months. We had a vesting schedule in place. I currently have 20% vested.

I've agreed to sell back 15% of my vested equity and stay with 5% to help the company succeed. We are about to start raising. So far we've received $25k investment via SAFE + $10k grant w/o equity.

Is it reasonable for my cofounder to be asking me to sell back the 15% vested at .00001 (the price I paid two yrs ago)?

What other options should I consider?

Thanks!