think I betrayed my bf

keep replaying and thinking about a time i walked to the station and got the train with someone from my course in september and feeling more and more guilty. i dont think this person is my type physically and i didnt think i was attracted to him at the time but looking back he made a joke about being a posho and i laughed and think maybe i felt attraction to him in that moment and I think I was attracted to his personality and voice and sense of humour and the fact we shared interests and he was easy to talk to. and when the person we left the pub with went off in a different direction and we looked at each other and awkwardly said ‘hello’ and smiled i definitely felt a vibe like he was interested and he thought i was interested and i think i enjoyed that vibe bc it felt exciting to think he was interested in me and i had a giddy flustered feeling which makes me worry that i was interested too, at the time I didn’t think I was bc i was so anxious about bringing up my bf the whole time and waiting for an appropriate moment to do it. but i feel like it was wrong to intentionally walk with this guy and get the train when i had that excited feeling and attraction (which I didn’t really understand or accept at the time) but i did enjoy talking to him and wanted the conversation to continue but i think i also wanted to gauge if he liked me bc i wanted the validation but at the same time i was thinking no when a good opportunity to mention my bf pops up and it feels natural do it then do it and i did but that was probably after like 20 minutes of conversation and i should have just forced it out sooner. i also had thoughts like you could cheat rn, what if you’d be happier with him and imagine if you dated and i didnt want those thoughts but i was scared bc they felt like real desires. i don’t think i actually wanted that but i think i did indulge someone who was maybe interested in me bc i enjoyed the attention AND even worse bc I maybe felt tempted? bc I think if I had been single I wouldn’t have pursued him, which meant I did feel some romantic attraction right? I’m worried tha I felt a bit of discomfort when I mentioned my bf bc I wouldn’t get the ego boost of knowing if he liked me, which is bad enough, but now I also think a part of me thought ‘what if there’s something here’ and was sad I couldn’t find out how it could have turned out if I was single. I don’t know if they were just intrusive thoughts, but I felt really conflicted bc I did emjoy talking to him a lot. but i love my bf so much and dont want to be with anyone else, but at the time we were kong distance and think I was feeling disconnected and missing the thrills of flirting that come with being single - having said that I was careful not to flirt - did i cheat/want to cheat?

i told my bf the facts of what happened (I walked with him, got the train, mentioned my bf later when it felt natural and looked for an opportunity beforehand to do so) I said I felt ‘platonic chemistry’ and a spark which i thought was just the excitement of possibly being liked, but now I think it’s pretty clear I was attracted to the guy and felt a pull towards him and so I haven’t told my bf the full truth. I don’t know what to do can someone please advise - ik sit with uncertainty etc but this is a serious real relationship concern and I owe my bf honesty