My girlfriend signed up for internet brides.

I met the love of my life from an international dating blog two years ago, so basically, my girlfriend and I have been dating for two years. I wanted to marry her so I asked her two weeks ago. Unfortunately, she said NO and it broke my heart into pieces. She said she's not ready to build a family yet and I understand. I couldn't accept what had happened. For one week, I have been unwinding but it only made me miss her more. On the following day, I went to her house just to see her. But when I arrived there, her brother told me she moved with his fiancee abroad. I didn't want to shed tears in front of her brother but I couldn't stop it. She signed up for internet brides two months ago and that's where he met his fiancee. I didn't know what wrong I did for her to leave me like this. This feeling is killing me. What should I do?