Tee I have only just seen this. I am so very sorry to hear your news. I can't begin to imagine what you're going through, but know that we're all here if you need to talk.
I've had this happen twice in my family (my brother's 2 sons) so have some experience, and know how hard it is just from an aunt's perspective, so cannot imagine what you're going through.
Like others have said, if you feel up to it then it might really help to talk and not bottle things up. I really hope you have a good support network around you.
Lots of love x