You need to remove one of the spokes from the damaged side of the wheel as they are usually a different length between sides and to get a correct size of spoke since they come in 1 mm increments as well. It is best to detention both sides of spokes to release pressure on all spokes. This will allow you to keep the wheel round when truing it back up. You will need a dishing tool to make sure the rim is centered to the hub or let the lbs true it for you. Also if the wheel is still true squeeze all of the spoke pairs and see if they are balanced in tension if not and the wheel is straight then the rim is slightly bent and replacing the spokes might make matters worse, wheel should be replaced at this time instead of repair.