What do I do now?

I gave up my son for adoption almost 21 years ago. I was only 12 years old and he was biracial so I was not given many options. I was placed in an unwed mother's home and started the process of finding my child's adoptive parents. After searching through many profiles, letters, and pictures; I chose a couple who I thought were the perfect fit. We had enough time to get to know each other well - enough I thought - and agreed to an open adoption with contact to be handled through the adoption agency. They assured me he would grow up knowing he was adopted and I chose this route out of love for him. The day after my son's birth, I traveled back to my home knowing that I had done what was best and having peace about it because of the agreement to open adoption. For a couple of years we had regular contact via letters through the agency then everything just stopped. I contacted the case worker via telephone, letters, email, and visits many times and was told only that they did not have the forwarding address to get any information. When my son turned 18 I again contacted the case worker to learn his whereabouts and provide an update on my information. She said that she was unable to provide me any assistance because it seemed that they fell of the face of the planet. I've been in the Air Force for quite a while so last year when I found out I have orders for overseas that will move me the month my son turns 21, I hired a private investigation company that specializes in adoption reunions. On March 1 they finally called to tell me they believed they had found them. Although I was provided the phone numbers and address to my son (who's away in college) I chose to contact the adoptive parents first. I did not know if he had been told he is adopted and did not want to introduce myself over the phone since a visit is not feasible at this time. After a couple of days of heavy praying and being afraid, the adoptive mom called me back. We chatted for a while very nicely, but she said that my son does not know he's adopted and they do not want to tell him. When I asked why he had not been told, the response was that it's just never came up. This I have problems with because my son had some severe medical issues as a small child that are directly linked to genetic defects in my family. He's also very tall, another from my family, where both of their families are not. Because I was losing what cool I had we got off the phone with the promise that I would write them and send pictures of my last 20 years. It took me 5 hours to write a 3 page letter to them. I rewrote it several times because I was trying to find the proper words to let them know that I have no intention of taking him away from them. This week the adoptive mom friended me on Facebook so I began another conversation with her in hopes that I could get agreement that my son be told by them. Her initial response was that I am a good person for respecting HER privacy. Her second response is that she is unclear what my intentions are and the best thing for him is to be left alone. So I again made it clear what my intentions are. I want to meet my son. I want him to decide whether he wants me to be a part of his life. I have spent every day of the last 20 years wondering what is going on with him. Now her response is that I have no rights and it would be selfish, unfair and morally wrong for me to contact him against their wishes. I do have another son but had several miscarriages and ended up having to have a partial hysterectomy. I don't know if my thoughts would be different if I'd had the amount of children I could have but it seems vital to me to have him make the decision on his life with or without me. There are many medical issues that he needs to be aware of even if he doesn't want any relationship. I don't know how they would explain those since most are genetic and are not present in their families. So my questions are: Do I have any rights where my son is concerned? What do I do now? I'm leaving the country for 3 years in a little under 8 weeks. Thanks for any responses or support. `A