You don't need a grip, you need a hug. And possibly a good cry too.
I have RTFT and have just relived the loss of my beloved dog last year - he was my first baby and bastard cancer took him away. Funnily enough we also went on holiday the next week, kids were OK and I just about held it together in the daytime...
I still think of him every day but it is not as painful now, and I am able to smile at thoughts of him as well.
We had two other dogs when he died and we still have them. I don't feel the same about them as I did/do about him though. About 2 months after he died someone called the humane society where I volunteer wanting to surrender a 12 year old mastiff cross. I said I would take him instead. He was exactly what I needed - a gentle old soul that needed to be looked after. I see so much of my old boy in him.
I know your boys are hurting but what wonderful boys to be so upset over the loss of a beloved pet, that says a lot about their character.
Years before my old boy was even sick I used to dread the day coming when I knew he would go, every birthday I was grateful that he had made it to another one. I didn't think that I would be able to cope but in the end I did because of course there is no choice. I did the best I could for him and when there was nothing else that could be done I let him go.
In some ways I coped better at the time than I did a couple of months later. At the time I was just dealing with practicalities, he had been diagnosed a month previous, I was trying to feed him a special diet, he was getting a separate walk from the other dogs, he had hemangiosarcoma so I was constantly expecting a ruptured tumour and a collapsed dog - on every walk, every time I left the house. When he was pts I was sad but more than that I was relieved that I didn't have to worry about him any more and I didn't have to worry about not knowing when the time was right, or him suffering because I didn't see the signs. A couple of months later the relief was gone and grief hit me for real. I'm sure it is the same for you, you had a massive shock and now it is really starting to sink in.
Unfortunately the only thing that will help is time, and it doesn't take the grief away but you do get used to it.
I am so sorry for your loss.