Ah man I'm so sorry to hear about this sad news :(
There are many questions you will have on the "how" and "why" but this isn't important right now. Channel your energy and your focus in to being there for your sister and send those positive vibes her way for successful treatment.
I know the emotions you're going through and my thoughts are going out to you right now. STEEM isn't important at this moment in time, your family needs you Joe, stay strong my friend.
Thank you so much my dear friend! I just needed to vent out. Am really touched by your kind words and prayers.