I don't know if it's the right thing to say, but I have a friend who's mum isn't around anymore.
He always says that he wishes that his mum fought more, fought to show him the lesson of never giving up.
Don't give up. Life can be wonderful. Please don't give up. He loves you and needs you so.
Don't think that he'd be better off without you, it's simply not true.
Sending strength your way.