I Need Help! PLEASE!

Let's just call him "Mike".
Mike loves me. I love him. We are sort of dating. It would be perfect, if he did not have an actual girlfriend. But he doesn't love her. He is stuck with her for a few reasons: she is crazy-obsessive. She stalked my Facebook page because his relationship status said he was "married" to me. She would comnent on my pictures and read all the statuses. Of course, I blocked her. Another reason, people will give him so much drama if they knew he was dating me Insted. Another reason, all girls get easily attracted to him. Which irritates me because they only care for his looks. I actually understand him. We have so muchin common.
So.. He is stuck with her. Due to that, I have to be a secret. I can't be seen by his friends, I can't talk about him to people that know his girlfriend, and obviously, I can't post anything about him on facebook.
As I said, we love eachother. We care about eachother. But his messed up life affects us both. But I don't know what to do. Can you guys help..?