Such terrible news. Sincerest condolences my friend.
I know what its like to lose loved ones so close together within a short space of time. In the early eighties I lost my mother, grandmother, grandfather, three uncles and an aunt in close succession. The last of those (chronologically speaking), my grandfather, died on December 25th. Hows that for a Happy Christmas.
The only two pieces of advice I can give you are firstly, to just hang in there, time does heal all wounds, even if you will always have the emotional scars. Secondly, be thankful for and cherish every moment you spent with them, because not everyone gets to grow up with their loved ones present.