Dana,
I am so sorry for your loss. There is nothing that can replace Andy, but I am sure a new puppy will make you feel better. This is a horrible thing that does happen when people do not keep their pets on a leash, big or small.
I have 2 VERY big German shepherds and my yorkie baby Junior. I never walk my shehpherds without a leash, for this very reason. However, I have encountered people who dont keep their little dogs on leashes, and they come running up to my dogs! Thank heavens they are trained and nothing bad has happened to this date. I will continue to train and work with my dogs to prevent as many bad dog encounters as possible.
Best wishes to you and your puppy. Sounds like you have a lot of love in your heart to give!!