Immediately leave toxic business partner; seek better freelance clients

The original poster is in an exploitative and unhealthy working relationship. The business partner's actions – firing due to a medical emergency, inventing performance issues, reducing payment for unstated deliverables, and expecting unpaid strategic work – are severe red flags. The '24/7 availability' for modest pay and constant stress make this unsustainable. The 'better opportunity' for the OP is to immediately terminate this engagement and focus on finding new clients or a full-time role that values their contributions, offers fair compensation, and respects professional boundaries. There is no hope for 'rescuing' this relationship; it's detrimental to their mental health and financial well-being.