I think I found her...I need some advice...ASAP!

GOod morning all. Well, I am pretty sure that I found my birthmom. Like 99% sure. SO.....my husband and I and 2 friends are taking the day off of work tomorrow to go see her. She def. doesn't know we are coming or that I was looking at all and I'm pretty sure she was def. not looking for me. Anyway, I need some advice on how to approach her and what to say. I'm really nervous and excited all at the same time. I'm glad I know where she is, but so worried she is going to shut me out. I don't plan on demanding a relationship with her, but I do feel like I deserve at least one conversation where she will answer all my questions. I have a feeling I am really going to surprise her when I show up and say who I am, so I was thinking about having a letter ready to give her because I don't know if she is going to be willing to talk right away. But I also feel like if she sees me instead of just calling or sending a letter, I become a real person and it might be harder to completely turn me away forever. I guess I am just looking for some guidance on what to say and maybe how to soften the blow. Maybe a few good things to put in this letter. I'm very excited and so nervous and it is consuming my thoughts. The sooner I do this, the better. So any advice is welcome!!! THANK YOU SO MUCH!!!