Wish I could wrap my arms around you - I’m so sorry you’re at this place. I had to euthanize my first horse (cancer) and feel lucky that I was able to donate him to a university for research. I had to trailer him to the school, and they gave him the injection out of my view. While that may sound terrible, I don’t regret not being there for the final moment. I spent the day before with him just being with him and loving on him.
I do deeply, deeply regret not having enough pictures of him, and not keeping a clipping from his tail (although I see several people had a hard time doing this). I did keep a horseshoe, which I have had for 20 years now and will never let go. I would trade the horseshoe gladly for just one more picture.
Also, I never regret my decision to “send him home” before his condition got much worse. It was so very hard, but I am glad I didn’t wait until things were bad for him.