In moments like these are very difficult to say something for that I lack words; the loss of a to be wanted is as if one lost a part of the body that won't be able to never recover, but it is always the comfort of having carried out all the humanly possible one for that dear being. 
I tell him these words since I lost my father 23 years ago because of the same illness and you the hard thing that it is this, and you of the lived moments. 
Let us trust God and in Jesus Christ they are the salvation sources and that they help us to overcome all the bad moments that play us to live, and that they help us to retin the wounds. 
I want you the best thing and that you soon can find the comfort, you also have all my support and I believe that that of all the members of this page. 
A strong hug....!!! 
Rodolfo