I have to agree with Paul. I wouldn't leave the puppy unsupervised around the GSD, with or without food present. You already know he plays too rough, so he should never have the opportunity to hurt the puppy. You didn't say how long you've had the puppy or how old it is, but this is not going to just magically get better over time. If you want to make this work, the GSD needs guidance as to how to interact with the puppy, which requires constant supervision whenever they're near each other. Leashes may be required in order to maintain control and safety.
Second, a few months of obedience training and some protection work is nowhere near enough. I'm sure you could find a good trainer more conveniently located who can help you. Maybe if you put your general location in your profile or this thread ("Northern California" covers a lot of territory!), people can offer some suggestions on where you can go. An 18 month old shepherd is too big and strong to not be trained how to behave properly. You really should have done something about him sooner, but it's never too late to start.
I also wouldn't leave a dog outdoors who is out of control (biting your husband, dragging your kids around by their clothes, he can't be walked on leash without going bezerk), and has already broken through your fence and escaped your yard multiple times. Why is he left alone in an unsecured yard?
You say you've tried everything you can to give your dog the best life, but I don't agree with that at all. And I don't mean that in an insulting way, I mean that there is plenty more that you can do if you're truly committed to this dog. Halo, my youngest GSD, who will be 4 years old next month was in 5 obedience classes by the time she was a year old - Puppy 1, Puppy 2, a Canine Good Citizen prep class, Family Dog 2, and Basic Manners 2. And then we worked with a private trainer, and then I put her in flyball classes, and now we race in tournaments. Her first class was at 13 weeks old, 3 weeks after we brought her home, but I started training her at home right from the very beginning. Like Keefer, my 7 year old, and two of our three previous GSDs, she's been crate trained, and still sleeps in a crate in our bedroom at night. I practiced NILIF (Nothing in Life is Free
) from the time she came home. I worked on impulse control every day, and default behaviors like sit, down, and eye contact. I spent hundreds of hours walking hundreds of miles to work on polite leash skills.
You're not going to like a lot of the responses you get here, and I'm sorry about that. But you can choose to be offended and get defensive, or you can take some of the suggestions and run with them. Good luck, I truly wish you the best.