Dealing with feelings I dont understand due to my nephews illness

My nephew was recently diagnosed with monosomy 7 and mds pre luekemia status. My sister and I are very close and our children are only ten days apart (15 months old). Ever since the diagnosis I have been dealing with so many emotions. Guilt (why her and not me?), depression (nothing I can do), distancing (Im not but Im having the feeling to), and to be honest there is some part of me that feels like it is wrong for me to be feeling ANY of these things. How do I cope with this? I feel it is not fair that my child (not without his own problems) is healthy and happy and I am watching him stack blocks and steer his power wheels, while she is in the hospital for 100 days of touch and go chemotherapy and bone marrow transplants. I find it hard to enjoy what I do have because I am shocked that something like this can really happen to a baby (my nephew ffs). Anyone know any websites with support groups or any advice how to deal with these emotions?