Don't feel guilty about that for one minute. She never had a chance from the minute you got her. There was nothing you could have done differently that would have made any difference in the outcome. You did a whole lot more for her than most people would have done and you can be proud of that fact.
She had a sweet, trusting heart. Maybe she wasn't betrayed, maybe it just happened, but dangit, someone should have protected her before I did. It makes me mad. I'm a sobbin' mess, but I do feel good that she had some peace and didn't die as horrible and sick as she would have on her own.
Thank you all, she was deserving of your compassion. :~D
I'm gonna go cuddle with all muhotherpets.