Bless you for taking in the poor little guy! He sure is lucky to have you and your hubby!
I think Maddie will adjust in due time. She may feel jealously at first which is totally understandable. Continue to show her love and attention, let her see you love the little guy, but try to make sure you have your special time with her. I think she will love you more seeing how you can open your heart to love another too. Over time they will learn to live together and will probably become inseparable!
When Honey Bear came home, both my cats were not happy with the addition to our family. They pouted, hid from her, gave me attitude. After a few weeks they all get along just fine, they lay together and play with each other. Just about every morning now, in my queen size bed, will be me, my hubby, Honey Bear, and if not both, at least one of the boys (cats)!!! Poor hubby is hanging off the edge of the bed!
Bringing home the little guy will be a big adjustment for everyone in your family. But once you all find the comfort and settle into to life with everyone, you will wonder how the heck you did it before!
Best wishes and good luck!