My boyfriend ex best friend.. help..

( Btw we are all 20 year old just to add that we are not in our teens )

So at the start of the year me and my boyfriend went and met up with his friends.. there was this one boy who was so so sweet and gave me his coat because I didnt have one gentleman well we all kept meeting up and we would go round that boys house and watch film and just hang out well I got the boys number because my boyfriend rang him off my phone and me and the friend would talk over text and I ended up getting feelings for this boy and I went round his house with out my boyfriend in the middle of the night and came home at 5am but nothing happened then we would meet with out my boyfriend again nothing has EVER happened between us we would just flirt and * act like we was together* but with out kissing and things just hold hands and cuddle and my boyfriend knows all this I told him straight away and we had a big argument but now we have moved pass but I still think and want to meet up with this other boy and I dont know why.. I have been with my boyfriend for 5 nearly 6 year I love him with all my heart. he is the only boy I have ever slept with and my first ever boyfriend I love him dearly so why am I still thinking of the other boy i feel so so guilty and i really dont want to brake up with my boyfriend i love him to much for that.. please no hate comments. Arrhhhhh what's wrong with my brain.. I just want to stop thinking of this boy and move on with my boyfriend and live happily ever after lol.. . it's making me depressed I really really dont want to brake up with him and 😭😭