Fear of the Unknown

As my family embarks on this journey into foster care/adoption the fear of the unknown is slowly starting to rear it's ugly head in more ways than one, it seems the closer we get to our first meeting the more it's appearing. My boys(who are about to be 13 & 11) are starting to ask more questions and express their feelings on why they don't want to share their Mom & Dad. We have yet to tell my soon-to-be 17 year old step-daughter, she doesn't live with us, I personally think she will be thrilled to have a sister. I have only told one person in my family, Aunt Kathy, she is very supportive. Every time in the past that I have mentioned adoption to my mother or my husband's parents they think I'm crazy for wanting to take on a problem child when I've been blessed with two healthy, intelligent sons. Statements like that hurt me to the very core of my being! Adoption is one of the greatest ways we as Christians can show the world God's love for His people after all He has adopted us with our many faults, sins & problems into His family. The Bible speaks clearly on caring for the fatherless, orphans, widows and underprivileged and I have desire that is not of myself brewing in me, I can promise you if this was all my doing I would have backed out years ago but this desire has been in my heart for 11 years. Even as a child I remember crying and asking my parents to please adopt me sister, to this day I wish that they had, it's a lonely world growing up with three brothers.