My poor (fur) babies

Its now the end of day 1 of (knowingly) caring for a diabetic cat. She now has to meal fed twice a day. So both my cats are getting half a can of fancy feast and half a scoop of dry food. Plus insulin shots right after eating for one of them. I feel horrible as this is a direct result of her being overweight. I just let them eat whenever they wanted aka graze. She's only years old.