My(29M) gf(31) runied our 20+ year old relationship by cheating on me

TLDR:I’ve been in a relationship with her since school, but now she’s dating her boss for a promotion, claiming she’ll break up with him in a year to be with me. She says it’s not serious, but I’m torn between waiting for her or moving on. My parents are conservative, and I’m unsure whether to trust her or if it’s worth the emotional pain.

Detailed story:
Me and my gf were in a relationship since school. I proposed her when i was in 4th. She was my senior. She was in 5th at that time. She accepted my proposal and our relation was very strong till 2024 sept.

We are in a LDR. So recently she changed her office and started working in a startup. And at first she told me that the md(managing director) is flirting with her so i said "Maje lele uske haha"(Make fun of him) and i was joking with her. Then she used to troll him whenever he flirted and sometimes she sent whatsapp screenshots where she would be giving a witty reply trolling him. And we both used to laugh a lot. But then something changed since january 2025. She stopped sending me those ss. So i asked her what happened and she said she stopped trolling him cuz he confronted her. So i said yeah okay etc. Then she started working late nights. Stopped picking up my calls and responded to texts late. And used to send those auto generated busy call you later messages.

Yesterday i thought of giving her a surprise and went to her place(we live 3 hrs away). So i went to her office and asked the waiting staff member about her. So she called some other office boy and said "he wants to meet md's name sir's gf". I was shocked hearing this. I said wdym by gf? She said they are in a relationship since 2 months and asked whether i was her friend or something. I said nothing and waited for her. When she came i confronted her. She said let's go out and talk like she was scared sm. She said he could promote her turn around our lives etc etc so she started dating him. She said "wait for 1 more year after that we can date again I will dump him by then."

Idk what to do. We were supposed to marry 2 years later. My parents know about her. And they are very conservative for them being in a relationship is like being in a marriage. If i tell we broke up idk what would be their reaction. Should I wait for one more year till she dumps him? Because she said all they do is hold hands and talk all lovey dovey or sometimes sext thats it as she told him she won't allow to touch before marriage. She told me she doesn't love him she's using him and after she gets her promotion letter and a much important job role in their parent company she would leave him and connect with me again till then she told me to wait.