You must get a lawyer now. Below us my thoughts given several decades experience As founder- You have a strong position here, since you built the products. D

You must get a lawyer now. Below us my thoughts given several decades experience As founder- You have a strong position here, since you built the products. Don’t walk away. The ultimatum is counting in you being non-confrontational and wanting to cave. This cofounder has betrayed your trust at this point, so some sort of exit is needed. Non-technical is a lot easier to hire- you can get marketing or whatever expertise he has easily. He should be the one leaving. Maybe offer to buy him out at current equity value paid over 20 years at %6 interest, secured only by company stock. If he forces the issue he will destroy the company in the ensuing lawsuit. So this is a mutually assured destruction situation. What is the ownership of the software? Did you retain rights to it? If you are forced out can you recreate the company quickly using the software you already created? Get a lawyer, now. You need an advocate who is ready to play ball and who can be the “bad guy” for you. Your cofounder will likely try to spin it, try to portray any resistance from you as evidence of bad faith, etc. Don’t let him.