@dyslexia,
Yes, it is a difficult situation. I understand.
Feral cats cause so much harm to birds & wild animals here ... you certainly wouldn't
want to encourage them. BUT, like you, I can't stand the sight of a suffering animal, which is in this predicament through no fault of its own. Very distressing. I suspect, like you, I would weaken & feed it ... & probably end up with another cat.