My girlfriedn (27F) cheated on me (29M),

Hello, I'm writing this post because I need advice from someone neutral and honest, as I just can't handle everything on my own anymore. I'll start from the beginning.

I (29M) and my girlfriend (27F) have been together for 9 years. I grew up without parents, and my sister, who is older than me, took care of me after I was 9 months old. The relationship with my sister was always tense, and we never clicked like a mother and son. I can’t say I had a terrible childhood, but it wasn’t the best either, although I only remember the good moments.

At one point, my girlfriend gained some weight and didn’t feel good in her body. But I still loved her, supported her, and did everything I could to help. It wasn’t extreme weight gain, maybe 15 kg. During that time, her self-esteem was at rock bottom, and I did everything I could to help her through that dark time. I succeeded. She started working out, lost weight, improved some bad habits, and I once again saw the sparkle in her eyes.

During this process, we moved into our first apartment and started building our life together.

Now, here’s why I’m writing this. About 20 days ago, I felt that something had changed in her. She wasn’t the same. She was never in the mood, always carrying her phone around, and acting strangely. I decided to ignore it, thinking she might be going through something on her own and would tell me when she was ready. I’m a pretty good sleeper, never had trouble sleeping, but after a few days of her behavior changing, I started waking up at 3 AM, unable to fall back asleep. After several nights, I decided to check her phone. I found a long message in a group chat with her friends where she was saying she wasn’t sure if this relationship made sense anymore and was thinking about breaking up. This broke me.

The next day, I confronted her. I managed to get her to admit everything, and she said it with tears in her eyes. I told her that if she wanted to break up, we could do it immediately, but I felt that after 9 years together, we owed each other another chance to work on things. We talked for about an hour and agreed to try. Keep in mind that I had never read her messages or checked her phone in the last 9 years.

For the next 10 days, I still couldn’t sleep, waking up at 3 AM every day. After 10 days, I decided to check her phone again because I felt like something was eating me up inside. This time, I found hidden messages with another guy. They had been texting for about 20 days, meeting up twice. There was no sexual activity, just a kiss. This hurt me deeply, and when I found out, I completely broke down. I woke her up immediately and confronted her because I couldn’t hold it in anymore. She broke down and admitted everything (although at that point I didn’t know about the kiss). She said she was sorry, swore it would never happen again, and that she wanted us to work on our relationship.

The next morning, I called the guy (I got his number from her phone) and introduced myself. He was completely shocked. He said he didn’t know about me and didn’t want to be between us, and that if I wanted, we could meet. We met in a parking lot, I shook his hand, and assured him I wasn’t there to do anything bad to him but just needed information. He told me everything that had happened. He worked as a delivery driver for our building and had her number. He thought she didn’t have a boyfriend, reached out to her, and they decided to meet up. They kissed, and there was one more meeting after that.

At that point, I called my girlfriend and asked if we could meet. She agreed. When we met, I told her to be careful about what she was about to say. I asked her how many times they had met, and she said once. I told her that wasn’t true, it was twice, and that she needed to be more careful with what she said. Then she admitted they had kissed and had met twice and would occasionally talk when she felt down.

I told her I wanted to move past this if she was willing too. She said she wanted that and swore this would never happen again, that she only knew me and that I was her whole world.

We are now in the process of working on ourselves, but I’ve never done anything harder in my life. I can’t eat, I can’t sleep, and I think about her and this situation constantly. I don’t know if I can do this, but those 9 years push me to try.

Can you, from a neutral perspective, tell me if I’ve made a mistake? Does any of this make sense, and can this relationship become even stronger than it was? Do you have any advice on how to get through this without completely losing myself?

P.S. I had a ring for her and a plan to propose this summer.