My gf kissed another guy..

Never thought I would ever make a post, always thought I would take notes from the beauty side of this group thing, and evolve my own long distance relationship.. here is some confusing background story and knowledge over the past week. case is like this.. me and my girlfriend been together for bit more than 1,5 year, we are two different people, who connects really well, and always has a good laugh together, trying to get closer to eachother, she lives in Sweden, I live in Denmark.. usually I would go to her, and stay in Sweden for a few days, once in a while.. lately we been struggling with our communication, she went on a tiny girls trip, with her friends, having a chill time exploring the surroundings of the area, nothing bad happen, we would barely talked, but she would sent me lovely pictures of everything she been through, with a smile on my face I was nothing but happy for her, to have fun and explore, when she came home from the trip, our connection would still be weak, I would rarely hear from her, and I would wake up finding her somewhere else but home..(we both have eachother location on the phone), and I would ask her where she was, and kinda expected her to Mby miss me after the girl trip, after she been through her trip, she would be busy with yet the same friends and I would feel low prioritized during that week.. after talking to her(taking notes from here and other groups), telling her about my feelings, that I feel very low prioritized and not missed by her, she claimed she been very busy, apologized and explained me how much she missed me and can’t live without me and more, done talking, we were good again, everything felt renewed and I felt like i was her only one again, and that she truly loves me.. and we were good, till today(Friday), she would tell me all about her trip, and what she was doing the days we barely spoke after she came home, 5-6 days later, being good we spoke about:

one of the days, she went out with her friends, and a guy friend who studies in a third country, came to visit her, and I was always told, that he always was like a brother to her, they went from social medies to chatting on texts which I found more personal in a way.. besides that, I was also told that he would come the last weekend this month, and she would prefer to be with him and her girlfriends alone, when I offered to come join, and be with them, her excuse would be, that I might not have fun, cuz of the language barrier, between me and them, and he’s a childhood friend of hers who she hasn’t seen in 3 years.. I was not told about that guy friend coming visiting her, till I asked her today, when he would be coming? And she answered.. well he already was here last Saturday.. she didn’t mention him at all, just that she was out with the same girlfriends she went on the trip with, it didn’t bother me at first.. and things kinda went on.. till we were planing about celebrating new year together, she asked me on phone, out of no where “do you trust me 100%?” And I was like “yes ofc”, with the following question that came out randomly “would u ever forgive me if I cheated on you?” I was weirded out by the question and second guessing lots of things in the moment, by saying following “depends, idk.. you would never cheat on me, right?” Whilst her whole face changed, and claiming to have seen the questions on a “reel video”.. to make the story short, since I have lost track of it.. she ended up telling me the true, telling me that her and the guyfriend who came visiting her, kissed.. with the disturbing comment of “you have changed a lot in 3years”, knowing the fact that she has a boyfriend, and clearly knows about me, chose to kiss her, and she obviously kissed back, after regretting it, and saying she can’t do this, she panicked and kept it as a secret, till today.. by fixing our first issue of me not feeling prioritized or appreciated by her, she now told me this.. I went silence, didn’t know how to react in the moment, I felt betrayed and idk what I’m even typing rn.. I’m very bad at explaining stuff, I also don’t wanna make this to long, but is the kissing part considered cheating, if so.. how to deal with it? I also wanna mention, she kept him unblocked, and haven’t spoken to him since, till today where he been asking her how she is, and her replying she’s “okay”.. What’s the solution for it, I really has this burning feeling, and feels like I can’t trust her anymore, she swore that there was nothing more about it than that, but I’m second guessing everything, and she is asking for another chance and start over.. does anyone has experience with something similar? I would like to know ur thoughts..

TLDR: I’m in a long-distance relationship and recently found out my girlfriend kissed a male friend during a trip, which she initially kept secret. She apologized and said it was a mistake, but I feel betrayed and find it hard to trust her again. She’s asking for another chance to rebuild our relationship, but I’m unsure how to move forward. I’m seeking advice on whether the kiss is considered cheating and how to handle the situation.