I do understand the way you feel. Every one of us has done things that we aren’t proud of. You have to stop beating up on yourself because your guilt will consume you. Yes, what you did was wrong, but the good thing is that you are no longer that person. That’s something to be proud of!  You have to admit to yourself that you are a human who is capable of making mistakes. You can’t change the past, what you’ve done is already done. The best you can do now is to find a way forward. If it makes you feel better you can apologize to your roommate or offer to replace the missing item. But you can’t continue to live each day with the guilt. You have a whole life ahead of you, and you’re not the worst person on earth. We all have skeletons in our closets.