IRescue, don't worry or beat yourself up, I don't think you are horrible or abusive at all. If your mice were dirty and needed a bath, then its good you got them clean. I once and a while have to give my bunny a bath and I don't see it as abuse. Some bunnies even like to be laid in water

I think those other people are very mean to say that to you and make you feel bad, all you wanted was the best for your mice.