On the mail subject, I would take it to the post office and tell them this is not the correct address and let them advise you of what to do. Let it be their problem.
On the "getting things" subject, I totally get not wanting to deal with it. It makes things much more real. As long as you have stuff there, you can kind of pretend that it's not so bad, maybe it's not going to happen. But, it will help you feel more empowered to get a friend and just get it over with. Maybe it would be good to set a goal of when to call and arrange the day making sure that he's not going to be home. Then, take a friend to help.
