What do I do about my recent past, I need help?

I went through a very tough five years emotionally and financially. Everything bad that could happen happened. My best friend died, my parents, I went to hell and back. In desperation I took a "job" as a nude model. Some of my photographs obviously are still on the sites I worked for. I had a nervous breakdown and had no job it was the only way I could earn at the time. Oddly I don't feel bad about it, but I realize that photographs on the net last forever. Someone sent me an email, saying they had seen the photos, the person was unknown to me, and that they would expose me for who I am. In the meantime, after my breakdown I found a very good job, and am piecing my life together. How can I deal with a person who threatens me like this? and also protect my job from finding out. It has taken so long for me to get back to where I am today. Please don't judge me, I am a sensitive person and I need help.