I know it's hard when you've had a breakup and still have their belongings around.. especially if you are using those as comfort objects. However, it's often harder on the heart to keep those things (reminders) around than to rid yourself of them. Have you attempted contact in an effort to give him his belongings back? If you've contacted him and haven't gotten anywhere, what about donating them to a men's shelter or even the Goodwill? I'm sure there's someone who could use those clothes that he has left behind.
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--Nyx-- What an astonishing thing a book is. Across the millennia, an author is speaking clearly and silently inside your head, directly to you... Carl Sagan