That is not your case though, because infidelity hurts you profoundly and your girlfriend is a pretty weak character. She was in constant contact with two previous lovers for the first six month of your (official) relationship and even sent one of them a sexy pic. She was texting them while with you, in the car, at home and she only agreed to stop when you asked her to. She did not think how disrespectful that was for you and for herself all that time and when you finally talked about it, she was unable to put that guy in his place on her own and you had to interfere. But she maintained contact with them. A year later she revealed intimate details about your relationship to SB and also had contact with NB, but again she blamed it on the guy, couldn't impose herself and make him stop and you had to do it for her.Two years later when you discussed breaking up, she didn't want to, begged you to continue, but sent nude pics to SB. She even sent him a pic that she took for a special album for you.
She always said that she loved you, begged you to stay but she has allowed the contact with these guys for years, because nobody harasses anyone and if she really wanted to stop this she could have done it long time ago. You have frequent arguments, you're consumed in front of her lies and have been like this for the 5 years of your relationship because she disrespected you repeatedly.