I could tell by the things that you were saying that you feel guilty but you truly have nothing to feel guilty about. You've had a full plate for quite some time now and the fact that you still managed to help feral colonies is a testament to your love and dedication to them. It's truly sad about Bonnie but she knows that you love her and that you tried your best. Years ago, when I was actively involved in cat rescue and it seemed as though I was losing more cats than I was saving, someone once told me "Sometimes we can only save them for a day". And that's one day that they had food, love, and the comfort and warmth of the human touch. Prayers are going up for Bonnie that she'll live a comfortable life at the RB and that you will find sweet peace.