S.E.
Being a child whose mom did that exact same thing...I think it is inexcusable that your fiance isn't willing to either step up, or let his daughter go. This isn't about him...it is about his daughter. If he hasn't taken the time or effort to be a part of her life for this long, he needs to let her move on. It is completely selfish of him. He can protest all he wants, but in this day and age, it takes a couple of phone calls or an internet search to find almost anyone in the US. He hasn't been a part of his daughters life for one reason alone...he didn't want to.
My mom moved away, and I didn't speak to my birth father for about five years. Why? Because he would rather complain about the bad deal in life he got, and how my mom did this, that, and the other. He didn't even call my grandparents and try to find out how or where I was. In fact, the only reason he finally contacted me was because he had a fiance (sound familiar) and how do you justify not being a part of your child's life for that long?
I can tell you right now that there is no excuse for his lack of parenting financially or physically. His name means nothing to her, and he would be a much bigger man to want her happiness, safety, and security over his prideful need to saddle her with a name that means less and less with every day he does nothing to be a part of her life.
Sorry...divorce stinks...even worse is the fall-out of parents making decisions because of pride or genetic ownership.