Does she have the right to know?

Me and my girlfriend have being on and off for 4 months. We split up then get back together. But the first time we split up she had sex with her ex. He caused us to constantly split up and fall out. She also has hatred for my girl mate. Anyway the third time we split she swore she was done and would be meeting this other lad. Anyway we were split up and not being on contact for 2 month she told me to move on. So this girl she had hatred for stopped at mine and we did sexual stuff. I couldnt go the full way as all i thought about was my ex. Anyway she was meeting someone also and only a couple of week ago slept with him. She knows she did wrong and now were back together. I made one genuine mistake and deleted the girl i did stuff with out of my life. Shes making so much effort with me now and the happiest weve ever being. My friends know about my mistake and so do the girl ive deleted friends. Should i feel guilty has she slept with 2 lads? and i havent slept with anyone. I live with the guilt but does she have the right to know. We wasn't together, not even on a break. Were leaving the past behind and moving on. She doesnt trust me at the moment but she said she will eventually but how will she if she doesnt know about this. but does she really have the right to know??