I'm so very sorry to hear about Maggie Mae. I know how excited you were about bring her home. I'm truly sorry.
Maybe it just wasn't meant to be and that the right dog for you is still out there somewhere. Keep looking and contacting responsible breeders, ask your good questions and be satisfied with the breeders' responses and in no time, you'll find a wonderful, loving addition to your home.
There is also rescue. They also handle puppies, if you have your heart set on a pup. I'd suggest submitting applications to your nearby rescue organizations so that if a boxer pup comes in, you'll be on the list and have a better chance to save a pup and add lots of love to your family.
Again, my deepest sympathies for your loss.