Canuckgirl,
I think most of us agree with what you tried to do and good for you, I for one think you have a kind heart and only tried to help.
Yes, it seems that the "island" dogs live a different kind of life than most of us think a dog should live but still they are domestic animals who rely on us for their care and health needs.
My heart breaks for you just knowing that you are hurting right now, I know how easy it is to get attached and then have to let go, but just remember that you gave this dog a bit of happiness and love while you had her and I for one am glad!!
Good for you, you did all of the right things here....