I think adinva answered everything very well. It's a big adjustment and the feelings attached are something to get used to.
What has helped me through the unfairness of it all and those hurt feelings? Simply focusing on my daughters feelings and best interest. not on my own. Putting myself solely in her shoes and removing myself from the situation. My D says mostly with me, so there would be times when she was a toddler, she would cry like heck when he brought her back. Sure, I wanted to cry my eyes out. Didn't she know mommy is the one who is always there for her? If she only knew it was daddy who chose this? No, you just can't think that way.
A married friend reminded me sometimes her kids have preferences on who they spend time with that day, or who they are going to run errands with, or who they want to take clothes shopping. It doesn't only happen in divorce. That's what kids do. There may be another day she attends something with her mom and comes running over to sit by you. Occasionally my ex and I will take our daughter out to dinner together. Sometimes she decides to sit by me, sometimes she decides to sit by dad. It has nothing to do with us.
The clothing issue makes me laugh now because it's been ongoing since our D was a baby. We split when she was a baby, and as babies do, she loved to pull off socks. She spent most of her time with me, But as a busy full time working single mother trying to raise a child practically alone, I couldn't chase after socks. he would always complain about socks not coming back and told me I need to replace them. I bough a package and threw it at his head.
My daughter developed a complex over "daddy's clothes" and mommy's clothes" I hated she got anxious about it. I always reminded her that they were HER clothes. Even the other night she said "should I put on daddy's underwear?" I told her she would look quite ridiculous in her father's underwear.....
So, we try to give clothes back. She knows who's home they come from. And if she wants to wear something she makes sure it gets to the house it needs to. Sometimes I don't realize it, and I have stuff from his house for a while, and he has stuff from mine. it'll never be perfect.
I guess I lucked out with the artwork because he doesn't care to save anything. I've got it all. But no policy on it. Whoever the kids bring it home to, they bring it home to. If you would like some of your kids artwork, have them make some at your house.
Yes, it is unfair, it stinks and it is certainly and adjustment period. But it can't be changed, so you can only make th ebest of the situation and it will come together in time.