Because you love her, she is your daughter.
First, I think you should think of what you should do if she's not your blood relative. What difference, really, at this point does it make whether she's blood related to you or not? Your wife isn't blood related to you, and she's certainly your family.
I think you should just leave it alone and forget you found out whatever piece of info this is.
Hi, yes i think doing the test would be best to confirm this.