Reply and say "That's not good enough." Nothing else. Makes your position clear and leaves the ball in their court. You still have all options available to you, but might motivate them to act.

Sadly, unless I'm misreading the situation, the relationship is likely broken enough that you wouldn't want to continue with them. You'd be either going it alone with your codebase or asking them to buy you out, subject to you seeing it through to launch, perhaps?

If you can negotiate a payout rather than equity, it might be a better return given their networkers aren't networking.