How not to be sad when your bio daughter does not want to see you?

I gave my daughter up almost 25 yrs ago. It was the hardest decision I have ever had to make in my life. I hated that I made that choice. I've lived with that decision all my life. I would of kept her but I was talked into my mom and other people telling me how am I going to take care of her. Well I waited all my life to find her. I hunted over the years before she was 18. I was lucky that I had her name at least. It was a closed adoption. Well I found her in Jan 2006 it was the best day of my life. Well it didn't keep going like that she has been distant the last 5 years. I have tried so hard. I am so broken hearted. I don't know how to deal with it. I know I have to understand how she feels. I never wanted that for her. She had turned out to be a amazing beautiful person. She graduated from Highschool and she is in the Airforce. Her Adopted Mom passed away with cancer before she graduated from highschool and I found her on her adopted mother's birthday Jan 17, 2005. I really thought it was meant to be and God and her mother had something to do with the reunion. But I don't know what I did wrong. I have tried so hard to reconnect with her. The other thing she has been away a lot in the service. The only way I know she is ok is facebook and that is how I found she was back from Iraq. She doesn't call or anything. I have gotten a few messages on fb. She said she was going to come by but never did. I am so sad. I love her. I just have to except it and move on. I do have two other children a 2yr old girl and a 4yr old boy. I had the boy in 2007 and the girl in 2009. I waited all my life to find her and try and build a relationship. I just have to move on and take care of my other children. My dauther just doen't need me in her life. You know I thought that this would happen one day that I would find her and she would not want me. I did always hope of a happy ending. I love you so much my beautiful sweet daughter!! I only want what is best for you. And I guess this is what is best for me to move on and let you go. But I will never stop loving you and you will always be in my heart. And one day I hope you can forgive me. And maybe one day we will meet again in heaven. :-)