Need serious objective advice

I have been in long-distance relationship with my girlfriend of 4+ years for most of the time of the relationship. She is my first love, but she left the UK to go to her country, China, a few months after we started our relationship. I invited her several times to meet me but she rejected, which resulted in not meeting in person for 2.5+ years (!). I patiently waited her for years hoping that she will keep her promise to come back to me. She always had excuses for rejecting my invitations. Then, one day I found out she was betraying me behind my back for years having sex with another person. I found it out because I was contacted by that person (the one she had sex with) because at that time she also started having sex with another (!) new person. Instead of apologising to me, she blamed me and deleted me as a contact. My heart was broken, I couldn't sleep, eat or study for days. Then after some weeks I found a girl (obviously I had broken up with my girlfriend by that time), but anyway, that girl and I stopped seeing each other soon. My first love asked me to be together again and I accepted since I have completely forgiven her about having sex with those two guys behind my back for years. Then I even went to visit her. Still I am waiting for her and another year has passed with multiple rejections of my proposals to come to meet me. Now she says that the reason why she is not coming is because her parents don't like me (!) and the reason is because they think that if I loved their daughter I wouldn't find another girl just some weeks after breaking up with their daughter (!!), which means that they have a bad opinion of me as a person. I am speechless of all this and I thought I would be appreciated for accepting her back and forgiving her, but what I am told by her is: "I am not like you. I wouldn't find another partner so fast after breaking up. I doubt that you love me".

Can I please listen to some serious objective advice about these? Also, do you really think it's correct for her parents to have a bad opinion about me? My girlfriend said that I don't understand, and so I am posting here to receive objective advice.