I read a lot of posts about losing a much loved pet, and it applies to me also. The pain is almost unbearable, and if you have had to have your pet put to 'sleep' then the guilt can be too much to bear.
Our pets give us so much, unconditional love, they don't care if we aren't fashionable, are in a bad mood or even if we don't wash occasionally, they still love us. We could learn a lot from them.
RIP Isla - you beautiful girl.