Thanks for everyone's kind words. It still feels very unreal to go from three rabbits to one in just a couple of months.
I wanted to share a last very special and precious memory of my beautiful girlie. I spent quite a while alone with Tan before I let her go. She was wrapped in a fleece blanket and on the examination table with me kneeling beside her, my head close to hers and speaking softly to her. She was very much still "with it", although mouth-breathing. After a little while she very deliberately lifted her front paw and placed it over the top of my hand which was resting on the table