Our cat is 17. He has a chronic stomach condition which we've been managing with steroids, special food etc. for a few months. He's been okay but in the last week has been refusing to eat pretty much anything; even cooked white fish or chicken isn't tempting him now. The vets have said they can't find an infection or other obvious cause so have given him fluids, a steroid injection and Vit B injection and we're going to see if he rallies over the weekend. It's becoming quite obvious that whether it's next week or not, sooner or later we are going to have to have him PTS 
DS1 is 7, doesn't adore the cat but is quite a sensitive soul. DS2 (3) is less sensitive but loves the cat. Any tips for how to tell them? Do we let them do goodbyes? Or not? I'm at a bit of a loss to know what to do tbh.