I, too, was raised by people, other than my birth parents. I wasn't told until I was an adult. Which blew my mind, as they had constantly insisted they were.
I spent 15 years trying to find the truth, until 2 years ago, I, too, did a DNA test through Ancestry.
I followed the links, trees and hints, much as you did, but mine kept going back to the woman who raised me, on Both sides. Frankly, I prayed she wasn't my mother.
I found a link between a second cousin, once removed and a more distant cousin, with the name Ross. That name wasn't on the tree of the woman who raised me.
Eventually, I learned the woman who raised me, is a cousin, once removed, on both sides. On my father side, her father and my Grandfather Bachelder were brothers, and on my mother's side, her mother was my Grandfather Harding's sister.
I haven't completed my journey into who I really was at birth, but, I look just like my Grandfather Bachelder, so I know I'm on the right track.
I've met several relatives, and have learned I was wanted, which has helped me emotionally.
I wish your ex the best of luck and hope he and his family can reunite, as mine is, slowly.