Seeking expert testimony is a sign of strength. A personal relationship with a caring professional is proven clinically effective.
I believe that I can help with this question.
You are both missing the forest for the trees.
The most important thing making your relationship work.
Here you have an issue that is going to tear it apart again.
Lets look at both sides as there is right and wrong on each side.
If he was to show his total dedication to you he would throw those shirts away or give them away.
If you were to show your total dedication you would say, let him keep the shirts. The relationship means more to me than those shirts.
Those shirts are a real irritant to you. They give you stress and anxiety. They recall a painful time in your life and should really be removed for that reason.
It looks silly or petty to him because he cannot empathize with your pain
Not caring about your feeling is a serious issue. Even if the issue is silly in his eyes, your pain should not be trivialized.
This should not be a deal breaker but it could become one.
Let me recommend this wonderful book where you can find answers to your communication with each other. This is, by far, the best relationship book of all times:
Let him know how essential your feelings are to your well-being and use the book to find the best talking points.
I shall keep you in my prayers for success.
Elliott, MAE, LPCC, NCC, CCMHC