I've been in a similar situation and I eventually walked away to keep my sanity. However, that being said, there are some simple heuristics you can try first:

I've been in a similar situation and I eventually walked away to keep my sanity. However, that being said, there are some simple heuristics you can try first: - if you have more power via your shareholder agreement, you can prevent your co-founder from running the company, effectively firing them, - if it's a 50/50 or they have more power, you can try to "disagree and commit" for a certain limited amount of time (e.g. 1 year) to see if what you "genuinely believe" is correct, or maybe they are more correct, In any case, my advice would be to avoid an emotional decision.