Pretty sad situation. My friend was also like this. He was with this girl for two years and somehow didn't manage to have sex with her which blew my mind (I found out after he told me the story and I asked her how much sex he was giving her.) So this guy cheated with her and this friend of mine had a physical altercation with the cheater guy and got into a fight. It was pretty brutal and my friend broke the leg of that cheater guy and he was hospitalized. It was pretty brutal but the girl still stuck with the Cheater guy after my friend and her broke up, and continued for 7 months after which they broke up.
Basically if you have any mentality of idolizing a woman, you need to let that go and realize your own values. Shes not a God whose untouchable, shes just a human like you. If you put her on a pedestal and do this type of disney bullshit you'll get burned. You need to constantly have sex with a woman and give her consistent orgasms. After orgasmic sex, a womans brain releases oxytocin which is also known as the Pairbonding or the Love hormone. There is a biological reason for her cheating with you (you hadn't pairbonded yet and she was thus more prone to cheating. )
This situation can never work out. There is no pure love. I went through this sometime ago. There is just infatuation borne out of weakness. I advice you to pursue multiple relationships while being non exclusive with multiple women Sexually. This woman who you're talking about can also be a part of that if you want. When you're having sex with multiple women, you will realize your value and all this disney tier pure love fantasy and the unrealistic expectations created by it will evaporate. Since you managed to get a gf, it is highly possible that you'll be able to have sex with multiple women at the same time as well. If someone asks you what yours and hers situation is and if you're bf gf, tell them "I just got out of a very emotionally scarring relationship and am unable to commit to anyone rn. It will take me some time to heal. I believe you'll respect my wishes." If they ask you if you're seeing anyone else, tell them the truth "No I'm not seeing anyone else. I have sex with x no of girls but I'm not dating anyone rn. " Basically this situation will come rarely and only if you're not careful enough. After experiencing abundance ,you can make informed decisions about the kind of woman you want to be with By CHOICE not some hormonal and societal thing like Fantasy Love that is literally a hypnotism situation.