What should i do now?

Hello everybody. I have a girl friend. We are in relationship since 2007. My gf was very sincere to me. She is very intelligent, loyal, loving caring. I love her also so much & im kind of a person with possessive nature that’s why I don’t like if somebody else talk or wana friend with my gf. This year my gf added a person on facebook but when I asked that why did she does thi then she said that person is her childhood friend and he is from Uk (while we live in Pakistan) and he is just a friend he will not do anything. I said ok. But after two months from that day my gf sliped off the track, as that person (the childhood friend) proposed my gf and I came to know with my own efforts that my gf said yes to him, and she hide our relationship and said to him that she is single.. after I came to know I shouted at my gf, then she realized that she did a wrong thing she was committed to me. She told all this story to her childhood frind but that basterd said he love her and cant live without her, and made a soft corner in my gf’s heart. He traped my gf. And in the end my gf left me for that person, I cried a lot, I tried to stop her, but she ignored me completely. But then in just five days that person betrayed my gf and made another relation with someone else. Then I forgave my gf and accepted her. But then after a week she sliped again as that childhood friend came back & pretended that he wasn’t in any relationship with any one, then she again broke my heart, I tried to stop her, and told that he is a flirt & just playing with her. But she didn’t listen to me & again he dumped her. Now finally my gf is with me. I have forgiven her. But after all this that my gf said YES to that person, and said that she also love him and hide our relationship just to show that she is single and ready to mingle, this thing is becoming unbearable to me, I also cant leave her bcoz I cant live without her I love her so much.. what should I do now????