It sounds like your family comes first to you. If you were to explain your situation and decision to your team the same way you’ve done here, I’m sure they would understand. My advice would be to plan your exit with this in mind, and try to make decisions that are best for your family, ignoring the impact on your company. Once you have your plan, do right by your company by communicating it as clearly as possible. They’ll adapt to your absence, and perhaps even find a way to become stronger in the face of losing you.