It's the saddest duty you have towards your animal but you have to be there to offer comfort to her. You will find the strength to act as normally as you can because you know that you must not distress her unduly. If you do this then as far as she is concerned it will be a routine visit. I am crying a little as I write this because it brings back my lovely old Kitten, who was PTS in January at sixteen. It was heartbreaking and I went to pieces a bit the moment he had passed away, but somehow you manage to stay strong at the important time when you are helping your cat to go gently.