You haven't asked for advice but I'm going to give you some anyway.  Hook up with some childhood leukaemia support groups.  Thousands of parents have trodden this path before you and their insight and support will be invaluable.  They can link you up with the best organisations to give you practical assistance - and there are very many for childhood cancers - as well.

You cannot help your son if you don't take care of yourself.  Your priorities will be changed by this and a lot of things will now seem unimportant, but don't let taking care of yourself slip to the bottom of the list.  Now, more than ever, you still need to laugh and smile and have fun.