My (M23) ldr gf (F22) started having a crush on an employee at her internship and seems to not want to be with me anymore.

Me and her have been in an ldr for 3 years. Just yesterday she told me she wants to tell me something coz she wants to let it out. My ldr gf told me she has a crush on an employee who is her sir that teaches her stuff at office. I was devastated to hear this. She cheated on me in her mind by letting this new guy in. She gave him space in her mind when I was the only one that was supposed to be there. She clearly chose to have a crush. Everyone in relationships have temptations everyday, but we resist those. But her, she just let it happen. And she gave me empty apologies and says stuff like" I already felt it, what can i do?" Wtf?? Is that how you give a genuine apology?? The way shes soo not empathetic after she just broke a promise is so crazy. Just a day before she told me, I made her promise to not have thoughts about being clingy and closer to other guys and she broke the promise the NEXT FRICKIN DAY!! I gave my everything into her, my whole mental strentgh, my care, my time. I missed soo much of my 3 years in life coz of her. And the way she just shows no remorse about the situation is soo fucked up. Just before she told me and since a few days back, she was acting soo uninterested in talking to me, like shes already decided that she wants to move on from me and be with that other guy. Theres soo many things that makes sense because of this revelation. Ive only wanted the best for her, I was such a good bf to her even when she was soo toxic to me, getting angry and verbally abusing me whenever i did something that annoyed her ( and its things like something like talking more about what i wanted to talk about for maybe 1-2 min with her when she wanted to do something else) her patience is non existent and her temper is so stupidly crazy. I was always walking on thin ice with her, caged up and always have to look out for what i say or do with her. All that care for nothing, I just wasted it on someone so toxic and selfish. I dont think we'll ever recover from this. Ive been ignoring her since she told me those empty apologies and making it sound like its not her fault and wanting me to validate those feelings and be okay with it. She was clearly showing signs of no interest in me when she started crushing on that guy. Shows that shed rather see or talk with him than me. She goes to office in the morning around 7 30am and comes back at 5pm, then she does her chores, has some chill time and then we talk for maybe 30 min. And then she sleeps soo early at 9pm, like wtf. If you wanted to talk to me, you wouldnt suddenly want like 9 hours of sleep. Shes just tryna avoid me and just block me from her mind to put that new guy in all the space in her mind. I felt soo betrayed and hurt. I havent eaten since yesterday coz i keep getting chest aches thinking about it. How could she do this to me man? Theres no point in talking it out coz shes gonna keep seeing that guy in her office and shes gonna start growing more fond of him each day. Even if by any tiny chance she says she'll get over it, theres no way i can trust those words, especially with me being an overthinker. She broke her promise almost immediately, how can i trust her with thatt, with her crush being right next to her there?! Fuck me man. She told me shit like "since your not replying, lets breakup? I tried waiting for u to reply but u dont so fuck it. Im sorry if i felt that way, but i already felt it, what can I do about that?" wtff is this stupid ass response and empty ass apologies. She destroyed this relationship as soon as she let the temptation of that guy be her new crush and telling me about it instead of fighting off that temptation herself like everyone in a relationship does almost everytime. I might be overacting because my mind may not be clear, but ive never gotten angry and sad with someone like this. So i would like your guy' insight in this situation. Thank you.