That's what I keep telling myself - that she had two years rolling around the back garden, with a clean and comfy house at night, porridge for breakfast when it was cold, mealworms and sweetcorn for supper some days - and that she had lots of time to feel the sun on her feathers. That she had the best I could give her after her horrible start in life.
And, yes, you're quite right - she went quickly, and I didn't have to make the decision to let her go (which I would have done, rather than let her suffer, if I had to).
As the note my daughter put in with her - "We'll miss you, sleep well little one".
I feel like my heart's breaking and feel so daft, getting so distraught about a chicken, so I guess I came back to the place where I asked for all my advice when I first got them - to this forum. Because I knew people here would understand.
Thank you for your replies - I can't tell you how much they help.