I know exactly what you are going through with the e-collar. Nakita had to wear it for 7 days and she looked so pitiful wearing it.

If your home, I found that if you remove the e-collar a couple of times a day, for a few minutes, then the cat can wash herself and feel a bit more relaxed. Of course when I took Nakita's collar off, she would go straight for the stitches, so I would have to put my hand over them to cover them. Nakita would spend up to 40 minutes straight cleaning herself during these sessions and I found she was more relaxed once I put the collar back on her.

Glad everything went well at the vets!