sensitive topic, adoptee's widow needs advice

Hi, I started a thread in the "adult adoptees" section called, "stuck in the middle." One of the people there suggested I ask about it here to see things from a birth mother, first mother perspective. It is not a happy subject though, just be forewarned. My husband passed away, he was adopted, he was given a letter and contact info in an envelope when he was 18, but, he was resentful and wanted to prove his love to his adoptive family by not ever opening it. He told me he never read it, but, instead hid it. We had a daughter together and he let her know how he felt about his adoption and showed her the movie, "Meet the Robinson's" so she may accept his point of view and just be appreciative to the Afamily and not have a need to know the birth family. He never wanted to talk about the issue, but, in the last year of his life he started having some major issues and started reading psychology books including, "The Primal wound" He was very upset and more angry after reading that. He passed away that year. When my daughter found out that he died, she asked me what her real last name was, and then asked me, "Don't you think they would want to know I exist?" I was shocked because she never talked to me about this subject before. She had held in all her perceptions until he was gone. I stupidly brought this up to the Aparents to get their perspective and asked them, "shouldn't we notify his birth parents?" and they told me No, I shouldn't mess with things and that it would only hurt them to know. Maybe they thought I wanted to meddle, but, I was asking them because I didn't know what to do to help my daughter with her questions. I see things differently, much more like my daughter. So it's been a while since he passed now, we are more stable, and have moved on quite a bit. But, I can't close his life because of this issue. My daughter wants me to contact the birth parents and tell them about her. She is the sweetest girl, and she is now a teenager. She has lost several family members, and the Afamily is fading away from her. She has mentioned that they treat her cousins differently and that she noticed we are not invited to a lot of family things now. They see it as "not making things complicated." When our grandmother died, I asked to go to the funeral and they said no. I think it is because of the pain it causes them to even see or talk to us. They prefer not to even talk about my husband, only like one comment a year. It is stifling. They also have taken family items from us and gave them to their other blood family members. They never come out and say it, but, I can feel it. And my daughter can as well. So, I try to not challenge them and accept that things are just different now and I let them do the inviting, I try to ignore all the pictures on facebook of their get togethers which we normally would have been invited to. I can't change how they feel and that's okay, it's a hard situation. I can't talk to them about this. I found out that I could legally search for the bparents, I hired a mediator, and she found them. I think they live in my town. I don't think they are married, but, the man did know about the birth. So now I am supposed to write a letter to the birth mom. I have written about five versions and none of them seem right. I don't know how she will feel, or exactly what to say. My daughter wants me to do this for her and she wants to be known and to know who they are. I feel insecure about writing a stranger with this news. I want to be sensitive to their feelings. I also think they should have been notified immediately, but, I was in no shape to handle that, let alone anything back when this happened. I want to do the right thing for my daughter and I want to know what a birth mother or father's feelings might be about receiving a letter like this. I feel selfish even asking any of you. If you have any input, please let me know. In the first thread, I did get some good advice so far, mostly about not saying too much too fast, and respecting their choice not to proceed at all, not giving them much in the first letter until I find out if they even want to know more. I guess my question is, would you be offended receiving a letter from an adoptee's wife? Would you appreciate knowing if something bad had happened? Would it be worth it, if you could know your granddaughter existed? I have only talked to one birth mom personally, who lost a child, in a similar way, and was notified by phone, by the Amom. And she told me she was glad she knew the truth, she always wanted to know him and the truth. Before I write to this woman, I want to be prepared, and empathetic to her feelings. I don't want to make it worse. I also need to step up for my daughter, and not chicken out. But is this the right thing? My daughter is prepared for rejection or reunion, she has a great open mind. She also chose not to wait because she doesn't want them to die before she gets a chance to meet them.