as has been said, Don't do it, keep contact to a minimum and enjoy your time with your kids.
I remember reading your original post or one of them, i can't imagine what it was like but i have no idea how you put up with that at all. good job on getting out, it was the best choice for your sake and the kids.
as for the earring, take it as a small concession, take it out when she is with you and put it back on when you drop her off. Also someone suggested this already but get a diary and record everything she texts/says in phone calls that is mental. screenshot texts if you have to so you have a case if she ever goes ape.