I've been lucky: I've had 2 dogs, & had to put both of them down, & I've had no doubt either time that it was the right thing to do at the right time. I know that can be hard to judge.
@Impious_Jade I’m sorry. It just sucks, even when you know it is the right thing to do. Your dog had a good life.
One of the hardest things about having pets is knowing that most of them won't outlive us. I've expected this loss for a while & that doesn't make it any easier.