Ask HN: 50/50 Cofounder leaving amicably. What now?

Cofounder has unfortunately decided to leave our company. We're equal shareholders. Our shares vest over a 4yr period with a 1yr cliff. Since we only incorporated in February, nothing has vested, but we are both on the board.

What is the course of action here? Is there a place where I can find a template for some sort f a separation agreement that would detatch them from the company completely, including any shareholding and board positions?

Product is built but pre-launch, and, unfortunately, we are also in the middle of our pre-seed. We've incorporated a C Corp via Stripe Atlas