Post reunion with birth mother What happened?

     I am an adoptee who had a reunion with my birth mother as well as met my biological sister 20 years ago. The reunion was emotional and joyful as we exchanged pictures and emails. We spent time in her town as well as mine to see each other in person.  She met my children and picked out a grandmother name for them to call her.  She was reluctant to tell her husband and children about me, but eventually she did. My biological sister visited me too during that time.

     Six years later, my husband and I were invited to my biological sister's wedding. I was concerned about the fact that my presence would mean my birth mother would probably need to tell her and her ex-husband's families about me as well as her friends. In the years preceding our reunion she had only told one person about me. I suggested to my bio sister that I be introduced as a friend of the family and she said no way.  My birth mother seemed fine at the wedding although afterwards she did an about face in our relationship. She disappeared. Letters went unanswered and phone calls weren't returned. She made trips to my home state but never contacted me.  From time to time I was able to make contact but I think her feelings toward me had turned to dislike. In the meantime I found my biological father's family and connected with them. Many of them live in the same hometown of my birth mother and bio sister. I recently returned from visiting them. I also visited with my bio sister and met her children who are 5 & 7. I didn't contact my birth mother or make arrangements to see her, as she doesn't seem to want me in her life anymore but I received this email from her the night before my trip. It had been years since I had heard from her. After sending it she went in person to see my bio sister and told her to have nothing more to do with me. She didn't comply. It sounded like a secondary rejection--an attempt to roll the clock back 20 years. Here is her email.

"Your sister tells me you plan to come to my hometown.
I don't feel that it's good for me to see you. I frankly feel you have a need to punish me for my giving you up for adoption. Our relationship consists of you needing to “out” me in front of family and friends for my “sin”. Then I must constantly make amends to you. You are my judge and jury and I am unforgiven.

I feel you truly hate me and have no compassion or understanding in your heart for me. It's all about YOU.
Now all you want to do is remind me and everyone who loves me what a terrible person I am. “Hey did you know your grandmother abandoned me when I was a baby. What do you think of that?”
Be honest with yourself. You really don't want to connect to our family but only to embarrass and punish me.
I'm nearly 70 years old and I don't need this. You really don't need to come."