I don't know what to do

I am sorry this is so long, but please bear with me. I am the adoptive mommy of a 15 month old boy who is the love of my life. Our adoption was supposed to be a closed adoption, meaning we did not want further contact from the birth mom. We were contacted by our birth mom through an aquaintance at work. The co-worker gave the birthmom our number and she called me to say that she wanted to give her baby up for adoption. After 8 years of firtility and three unsuccessful invetro attempts, this was the answer to our prayers. The birth mom stated that the birth father was not in the picture, that he was in jail in another country. We kept in contact with the birthmom through out the rest of her pregnanct, she called us the day that she went in to deliver the baby, and wanted to meet us after she gave birth. We did meet her, the hospital was very generous and gave us a room to stay in with the baby. The birth mom did not want any contact with the baby and signed herself out of the hospital 12 hours after giving birth. We took the baby home with us and he has been ours since. We met her again at the courthouse on the day that she signed away her rights, she stated that she did not know who the birth father was and so we went through the whole publishing thing etc., at the courthouse that day her father had asked my husband if we would send pictures through out the years of the baby. My husband said yes. The adoption was final last August. Since that day we have been constantly harassed by the birth mother. The birth mother stated that the birth father now wants the baby and that pictures would do FOR NOW. (like a threat) We had agreed to pay for my sons circumscision, but she said that public aid would pay for the rest and not to worry about it. Now she continually forwards the hospital and delivery bills to us. She also asks for pictures and progress letters. I have a very hard time refusing her phone calls (at work) and I don't know why I can't come to the point of telling her that I don't want any contact, I guess a part of me feels guilty that I get to love and cherrish this child and she doesn't. Both the birth mother and birth father are involved with gang and drug activity. We are starting to get scared of our welfare. ANY ADVICE> would be appreciated.