[TheFullStack]

This is not advice but as someone who does a lot of contract work, it is repugnant to me that a "client" even consider the option of simply not paying for services rendered. By your own account, those services were rendered in satisfactory manner. The fact you are considering lurching on payment puts you in a worse light than all the faults of your co-founder in my view.

Honor your commitments.

[joshxyz]

This. Just because you two fuckwits can't sort out your marriage, doesn't mean you can forget to feed the kids.

Give what belongs to them, then you two are free to fight over what's left.