I Rented an apartment in Minnesota w/boyfriend. We were there 3 years together and both moved out. The landlord sent a deposit check to my roommate and he has kept it all. He claims he had to pay his brother $50 to help him move his TV out and pay for a cleaning service to clean the apartment. I with help from Family and friends, cleaned it quite well. What legal recourse can I take. Should I sue the landlord or the ex-roommate.

You likely will sue someone. Was both of your names on the lease, if so sue the LL. If not then sue the ex-BF, I made an assumption there.

If the boyfriend has acknowledged receipt of the deposit, but refused to turn over your share, then you sue him.