To Work or Not To Work

This is the question.
I have reached a point where my body is not cooperating with me working full time in a demanding Vice President role of a Japanese Startup in Silicon Valley and caring a 3 month young baby and two other kids and managing a house and socializing with friends and keeping my long distant relationship with my family abroad fresh and energized.
My body has started giving in.
My mind says I can pull it off.  I know I can.  Yet I know it takes a toll from me.
My heart is torn between my professional dreams and my love and longing for my baby.
My ego feels bruised and defeated when I think about quitting.  As if I got defeated.  The ego cares about what people say; "of course she couldn't manage with three kids."
I feel so uncertain and the funny thing is that I think I am certain.  I just don't want to admit it.