My ex broke up with me slept with other people and now wants me back…

Hi, I hope everyone is good. This is something i just have to get off my chest.

I had been with my girlfriend for a little over two years when she broke up with me in college. She had said that it was because she wanted to grow and work on herself and that going to separate colleges was very stressful for her to balance her personal and school life. We lived in two separate cities that weren't too far away (about 45 minute train ride), and we would see each other at least once a week but usually more. While I must admit that at first I didn't see this as a problem, but after we broke up I realized that living in different cities is not easy, even if we are close. When we broke up it was hard for both of us as we loved each other tremendously, but I accepted it because I wanted her to be happy even though I though we could have stayed together. She had told me that she was doing this for herself and not because of other guys or other reasons. We agreed to not talk and we didn't see or speak to each other for one semester. After one heartbroken, depressed semester she reached out to me wanting to see me again. I agreed and while meeting she confessed that she had slept with multiple guys. She also said that she wanted to get back together. I was like WTF!? anyways when I asked her why, she told me she was not over me and that she did this because she thought I didn't want to see her anymore and it was the only way to get over me. She said she didn't enjoy any of it and she knows she made a mistake but doesn't regret her initial decision because she had personal growth or whatever the fuck… The truth is that since corona virus has caused our schools to shut down, we have been living in the same city and I have been seeing her more because Im definitely not over her, however I was clear that we are NOT back together. She agreed and said she will do anything for me. I know I'm happy when Im around her but I have awful dreams about her sometimes and it makes me feel like shit. I feel like she betrayed me, even though we weren't together, and I feel like she just completely forgot about me for several months just having fun at frat parties while I was struggling. I don't plan on seeing her again when I go back to school, however some part of me wants to get back together with her in the future. I still love her and I know she loves me but making the right decision is tough.

Am I justified in feeling like she betrayed me?

Is it bad to keep seeing her?

What is the best thing to do cuz I'm just confused…