Found out I'm the other woman, what do I do?

I've been dating a man I met at work for about 8 months. He has been very good to me. We were very happy.

I have since dumped him, but it doesn't stop there.

Here's what happened :

I went to visit a friend of mine, three states over. While my boyfriend was supposedly away on his oil rig job. He is gone for months at a time. Normal for his profession. We talked, we skyped. And he took very good care of me, made sure he made up for the distance.

My friend and I go to a movie, and long story short. I find him and this woman. Making out. In the same damn theater!

Turns out, she's his WIFE! Of 10 years!

This is now 2 months later, his wife is harassing me. She's gotten me fired from my job, I worked for a religious firm. (Property law, all that jazz) I feel horrible. How did I not know? How did he hide this so well? And why are they happily ever after , and it's like I'm the one who did wrong?

How do I stop this?

I am NOT a homewrecker!