Reaching out, spiraling down

As a mother, we feel it is our place to take care of our children. Sometimes we feel it is our place to help them, and when they are in trouble; protect them. When does this turn into enabling? How do we turn those natural instincts off? When do we force ourselves to stop helping and protecting and let them fall? How do we stay strong when we are falling apart on the inside? Why does motherhood have to be so unfair sometimes?