ex wont sign roommate change paperwork

long story short, my ex and i broke up a day after moving in together so that week i moved all my stuff back to my parents. the last day i was in the apartment i filled out the paperwork to get my name off the lease. all he had to do was sign it and turn it in to the leasing office. ive checked in with the leasing office for a confirmation and they have yet to receive the paperwork from him. its been 4 weeks. he agreed to pay the full rent and has already but wont just sign the paperwork…ive tried contacting him but he wont answer me. does anyone have advice on what to do? for the sake of my mental health and my renting history i dont want this to drag out any longer.