These are some very good points. It sounds to me like he has effectively been your employee for some time. If there is a third party that both of you trust perh

These are some very good points. It sounds to me like he has effectively been your employee for some time. If there is a third party that both of you trust perhaps you can have a three way conversation where you focus on the current situation and the best way forward that's fair to everyone. The key is to focus on "going forward from where you are." That's the challenge you are faced with. Why do you need to buy him out completely? Are you going to need him to help new employees get up to speed? Find a way to keep the conversation going and reach an amicable solution.