I'm very sorry for your loss. It doesn't get much more difficult than that.
I strongly recommend spending as much time with your immediate family as possible. I am sure that they will need you as much as you need them. Try building stronger bonds with them for a couple of reasons: it will be the best thing for all of you and it most likely would have been what your mom would have wanted. A strong family bond validates an individual's legacy.
I'll light a candle for you and your family when I attend mass tomorrow.