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Thank you for he information and your question and I am sorry to read about your situation. If your roommate was on the lease or you can establish that you had an agreement to share expenses, then you can file suit in small claims court for the expenses you mentioned. The process is fairly simple and you can read more about it by going to: http://courts.mi.gov/Self-help/center/casetype/Pages/SmallClaimsSH.aspx
If you prevail in your case you can also ask the court to award you court costs and reasonable attorneys fees for the time you spent pursuing the case.
Please let me know if you need any clarification.