I am on urge of break up.. Please help me?

I am going out with her since 5 months......before we were in our relationship she was not able to get over her ex, so I said a lie that ur ex said tht u r ually not attractive and stufff....so she started to hate him.... Nd she came with me...... Now one of my friend told her truth.....now she feels I am a lier and dnt trust me..... But she loves me a lot and not able to decide wat to do?? Please help me guys because I love her a lot.......