how did you become confident with difficult decisions

Alex • Blessed to be mom to our miracle IUGR baby boy! I've never met someone as strong and brave as he is!
We are faced already with so many difficult decisions. Decisions no one should ever have to make, but are crucial to every step for the person that means the most to us, our son. Of course we are flooded with hope too, that maybe he will surpass all expectations and make it to almost full term in my womb. 
But I am equally preparing To be a mom to a preemie, to a little fighter, our little warrior. And that life is so different than what I imagined when we got pregnant. 
The doctors ask us how much intervention we want invested in our baby if he were to go early. It's so hard because you want to give the answer, "do anything and everything you can," but it's not that simple. He can't have a terrible quality of life... that's got to be the worst thing. So where to draw the line. And honestly, I have no idea. So we told the doctors all of this. They understand, said we can play it by ear, we can just reavaluate as necessary if we need to. 
I never knew how hard this could be. Preemie moms out there, how did you do it? What helped you become more confident in these terrible decisions you had to make?