So sorry you are going through this.
I had had to put down my 36yo this past March after passed an impaction but developed an infection that didn’t respond to antibiotics plus she.just.stopped.eating.
Her spirit was strong to the end, she wanted to go out in the day time, watched all that was going on and was pleasantly surprised to have so much attention the last day.
Do as others have said, brush, love, feed, take pictures and hand walks as possible.
Make arrangements of how the body will be handled,buried or removed, as quickly as possible. That way you are not standing wondering if and when. Or worst for me, thinking of the body being out overnight which I know happens with an unexpected death or emergency situation.
Have the vet tell how they handle the procedure before it begins. I held the lead until she completed the 2nd syringe and then she took over, laying my old girl down softly as possible.
Bury your horse with what you want, she was buried with her show halter and the backhoe man covered her body with her old show cotton sheet. I should have put some carrots and cookies in for her journey.
The vet cut her tail so we can order a bracelet for me, a hat band for DH.
I took the surviving horse up to see her, it took him several days to adjust and completely accept she was gone.
Leave the stall door and paddock gates open for at least 24 hours so their spirit can leave and not be “captured”. I know it sounds weird but I did and I believe she was about for a short while before staying with those who had gone on before.
Remember all that made your relationship with you horse and know you are doing the right thing to ease his suffering. Cry and let go of the pain. It will lessen with time.
We will probably plant some sort of tree over her grave between now and spring. You may want to think about doing something for yours.
<<<<<<hugs>>>>>>