Need advice on girlfriend

I have been dating this girl for almost a year now and everything was going smooth even though she loved me more than I loved her. Few months ago, we started having alot of problems which destabilised our relationship and that was when I realised I loved her so much. I tried to set things right but she neglected and told me she didnt love me anymore. I still forged on and we settled back after weeks of continuous begging. During a period while I was trying to get her back, she told me she was travelling to see he grandpa somewhere and I believed her but just yesterday, she informed me that she actually cheated me on with another girl and she didnt go and see her grandpa and that she has also cheated on me about twice earlier on. She told me that she loves the guy she went to visit and that he loves her too. I asked her about us and she said she wants me to continue with our relationship as usual. I got so confused.. I even tried getting details about this other guy but it seems he is shrouded in secrecy and I dont even know how they met. She set a different ring tone for him and sometimes, she receives funny calls from people and I get the more confused. I love her much but I am confused on exactly what to do here. I need advice on what to do and how to tackle this problem right now. I'll appreciate help in form of advice.