I have had the privilege to raise 2 really great German Shepherds. My current Shepherd is a female. At 6 months old, she was a handful but with daily training she learned quickly. Getting upset and showing your emotions disrupts the "safety" and stability of the pack. Remember you are alpha--you are the PACK leader. A Shepherd will not respond well too this type of crying and emotions. It is not a healthy outlet for you or the dog. Poodles, Shepherds, Dalmatians, and Weimaraners are highly intelligent dogs and extremely sensitive to human emotions.
German Shepherds are intelligent dogs and training will not be difficult once you are committed to the training program. One of the reasons why many home dog trainers get little or undesired result is that they quit the program and do not remain consistent. Your best bet of having a non-aggressive German shepherd is to start the training from the dog was a pup. Then as the dog progress that non aggressive growth will be like a second nature. Remember that a dog is a dog and no matter the breed needs love and attention. Play with your dog and talk to the dog. You will be surprised at how great of an impact these little things have.