I understand how you feel, but don't give up on him. Both he and Zak need training. When my 6 year old grandson came to live with us, I took him to obedience training with me and Tink so he could learn the commands and Tink could learn to respect his authority. Tink never snapped at him but did play too rough for little kids (she was 6 months old and pushing 100 lbs). He learned "off" and "back" when Tink would get to rowdy and he did not want to play anymore. He even learned to heal her on a leash (which was funny looking because she really dwarfs him now). Xavier knows now that he sets the level of play with Tink, if he is rough, she is rough. If he is low key, she will be low key, etc. It is up to you, but I think training is absolutely imperative with people with big dogs and little kids even if the dog is mild mannered, the kids need to learn how to treat dogs (their own and strangers). We get complacant when all goes well but freak when there is a close call. Training, training, training! for people and dogs. Follow your heart and do what you need to do but consider this as an option. Good luck.