Your words speak a pain I unfortunately understand too well. We also never got a chance to have kids, and Tom would have been such a phenomenal dad. His eyes would light up when he was surrounded by little ones, he had such a way with kids. It seemed like our life was just beginning, and now its been torn apart. He deserved sooo much more than that. Like a cruel punishment, and like someone else said "you don't get off for good behavior". You have put it so well "My heart is breaking, in ways that are hard to explain. How can one be so lost, and broken and yet stil breathing?"
I know its not any help, but you are not alone in this. Hang in there, hugs.