Going through my first breakup.

Hello, I am a 20M going to turn 21 on March 10th. I am a BTech 2nd-year student, and I am going through a breakup with my girlfriend of 3.5 years. I used to have a crush on her when I was in school, then COVID happened, and we met after a few years at another school and just started talking on Instagram. After a few weeks of talking, I confessed my crush on her and told her that I loved her. She asked, "Are you serious?" I told her yes, but if she didn't like it, she could just forget about it. However, she said she loved me too. Then, after two years, we went to different colleges more than 700km apart. Our relationship continued, but I started feeling that she wasn't happy with me anymore. She loved only me, but still, I know she doesn't like or isn't talking to someone else, but she isn't happy with me. We have had many fights over the year, and she also started hiding things from me and lying to me. It wasn't anything serious, but I believe a lie is a lie no matter what. I always told her the truth and haven't told a single lie to her, so I expected the same from her. We had fights because of this. She always blamed me for everything, and she told me a few times that she would never be happy with me even though she loves me. She told me no matter what or how many times we fight, she will always love only me. A few weeks ago, she went to her college event, but she had blocked me before going to the event without even telling me she was going. She wasn't seeing my texts or replying to them; it was getting late, about 11 p.m. I was getting very worried about where she was or how she was. Then, at 11:10 p.m., she just texted me, "I was at a college event," and that's it. I got very angry because at this point I had called her more than 20 times. She never used to do things like that; she always told me if she was going out or if she would be late. So when I asked her why she didn't tell me before or reply to any of my texts, she just said, "Because you would get angry and ruin my mood." I know she loves me, and I love her too. I don't like anyone else except for her. I only want her to be happy, and as she said, she would never be happy with me, so I told her to break up. She didn't want to break up, but I had to be the villain and break up with her so that she could be happy and enjoy her life. Now it's been a few weeks, and she called me and told me that she loves me, but I asked her if she is happy now. She said yes, but she was missing me. But I am not happy. I can't explain how I am feeling. I haven't told anyone about my breakup. I don't feel like doing anything anymore. I can't do anything. I just feel like lying in my bed and crying all the time, i have my birthday coming in just a few days and i dont even feel like living anymore. I don't know what to do; I don't want to tell this to her. I don't want to make her feel guilty or anything. I just wanted her to be happy from the start and even now.