I want to save my relationship?

[Jeffrey s]

Me and my girlfriend have been together for 4yrs. We have been through a lot of ups and downs. It was a beautiful relationship though we had a lot of misunderstandings.
In the month of March she broke up with me after a fight and didn't speak to me for two months. I tried apologising and fix things..she didn't give in. I was devastated and unfortunately at the time met someone on Facebook..we started speaking and getting to know each other and things started developing me and the new person. My girlfriend found out about this relationship and decided to come back to me..she tried every possible way to come back to me..I was being a strong headed guy. Thinking that she wants to come back just bcuz she saw with someone else.even in the past she broke up with me for her ex and decided to come back to mesince I have always shown her love and accepted however she came to me..after a few days I got to know that the person that I met online was fake..someone was trying to get money out of me..during the times me and the internet girl spoke - there were instances where I spoke about intimacy,marriage and kids so and so forth as I was really devastated bcuz even after loving my girlfriend so much all she did was breaking up and coming back to me. Me Andy girlfriend got back after me realising that I have hurt her too much and also the account was fake..it was a beautiful relationship I ever had..until the last few days where she went into my Facebook account and read everything that me and that person spoke..she was devastated that I lied to her about marriage,kids.Cuz after we got back she asked me these two questions and I said I didn't speak about them and I just couldn't tell her about the whole thing because she was already having insecurity issues after we got back. I was thinking of telling her the truth but then before I could, she found that only Facebook. Now she decided to stay alone cuz she is badly hurt and tells me that she has lost her protected feeling widme