This is a terrible situation because you're probably working with a really terrible founder. Even if you end up holding on to the 40%, it's likely they'll try

This is a terrible situation because you're probably working with a really terrible founder. Even if you end up holding on to the 40%, it's likely they'll try to screw you hard in the future so be wary of that. If it's possible in the very, very nicest of indirect terms make sure they know they can get sued for these kind of shenanigans and it will ruin the company. Long term though, it's hard to say, because they'll aggressively want to take everything. Also: get a lawyer. (I should have said that first)