Ok on the topic of things that have to be settled post break up :
Shoes, concert ticket, or anything.
Consider that it's gone. Don't dwell on it.
For me, it was money (and a lot). What I actually did is playing the indifference game.
But I'm financially very solid, so maybe it's not the same things for everyone.
We agreed on an amount (keep in mind that I was kind of ripped off). And I gave it to her without even blinking an eye.
I basically bought my NC as it was the last excuse she had to initiate contact (I ignored everything else).
The thing is, do it with a smile on your face. "Fake it until you can make it".
The result is :
1/ You get back the power and show your frame. "It's nothing for me, I don't care, I value you as much as a pair of shoes, a ticket concert or some money. And on the top of it, you are petty because you go on all your way to settle such insignificant things".
More spinning for her (I know it matters to you all, to get some kind of validation that it matters to HER, but really, you shoudn't care as the goal of all this is healing, and become a better and stronger individual)
2/ No more excuse for initiating contact. It's a very important point. Because those excuses can confuse you. You ask yourself why is she initiating contact ? Is it really because of the shoes or concert ticket ? Or is there something else ? And it will cause you pain, a lot of pain.
After getting rid of those excuses, you'll know that if she/he initiates contact, it will mean that she/he wants a security net. You won't be confused anymore.
So stay strong, even if you know a contact is unavoidable. Do it with a relaxed attitude, unconcern.
Best of luck, friends