I believe dogs are like people in that no two are the same and every one is special and unique in their own way. A house full of dogs will never replace Max, he was one of a kind and will always occupy a special place in your heart. Now that you have Bailey, your heart will expand to include another special place for your new pup. Our hearts have a huge capacity for love and I think you can never run out of space. Just because you love and enjoy your new furbaby does not mean that you have forgotten or stopped loving Max. You must allow yourself to be happy again. While I feel the same as you in that I told my husband that the day Nikko leaves us, I don't want him to get me another dog, if I was as fortunate as you to get one, I would welcome him into my heart willingly. With time, your guilt will go away, but only if you allow yourself to realize that you deserve happiness again. Max wouldn't want mommy to be sad. Good luck to you and enjoy your new furry bundle of joy.
