Recently, me(23M) and my gf(24F) broke up, it was her decision and I don’t know what should I do. Do anybody have some advice?

We have been together for 2y and 6m, and everything seemed to be going ok, I just made up my mind that I will ask her to marry me. One day, some friends told me if we were ok, BCS they saw she took down the photos we had together on social media, it was like someone punched me in the stomach. After I talked with her, she told me that she doesn't feel right anymore, she feels she is wasting her young years, she is afraid the she doesn't do the things that she like, etc. And I tried to talk to her, about how she wants to do things, what has to change, and I did exactly that, but she said she didn't feel any change, even tough I did everything that we said needed to be changed. After 3 weeks of that, she said we should take a break, to see what will happen, to focus on our selfs, and get better(neither of us was in a good place mentally, me BCS of the situation, and she BCS of work, school and the feeling that she is wasting her life), and I tried to respect her decision as much as possible, I tried to give her space, to not bother her, I would have done everything if it would have solved our problems. And one night she went to another city, with someone else, her friend (25f) BCS they were both feeling sad (when I saw that she posted she is in another city I had s panick attack, BCS in one photo she was wearing the night dress I bought for her last time I saw her, and In the other photo she was in a messy bed, looking naked(I saw only her leg) and I couldn't see any other option of why would be there in that dress…and I called her to ask her what was that, that's when I found out she was with her friend, but the feeling she may do that with someone else left me so hurt. And we talked a bit and she was colder, meaner than usual, and she told me she doesn't fell like we are on s break anymore, she feel we are separated. I don't know what to do, everything I do, everywhere I go, I want her by my side, I want to do everything with her, but she doesn't seem to want the same thing. She said she didn't have the time to think about us and our situation, and it kills me, how she can't think about us, after we had been together for so long, after all the bad and good things we went through. Does anybody have some advices, how should I take my mind from that, how should I focus on myself, how to not feel sad when I think about her, about her finding someone else, about her being happy and ok without me, about her feeling ok without me?