Same argument with boyfriend what do you think

Im in 4th yr medical school and been with my boyfriend for almost a year and a half but have been friends with him for 4 years. I love him so much and i know he loves me too. I love our relationship but there is one thing we keep having bad arguments over and i just want to get other peoples view on it.
My bf has all of a sudden started bringing up **** that happened in first year uni. Ill just explain what happened. Basically durint freshers i had a thing w a guy lets call him Jack that literally lasted like a week. He was in the same friendship group as me and my bf. This guy stayed over in my room a few times we kissed and i gave him a handjob he asked for oral i said no we never had sex. But we did shower together once. Idk why i did this i didnt deep it but in my head he already saw me naked so when he proposed showering i didnt really mind. After that i started to just not be into it and i kinda got the ick and was not feeling it. Even tho i could tell he wanted to do more stuff (he didnt want to have sex) i never did i just didnt feel it. Not long after he thought i kissed my current bf on a night out (i did not) and after that we mutually j ended things. Fast forward many months later me and my current bf were spending lots of time with each other and were basically best friends but it always felt like it was more than friends. On a night out i kissed him. My bf was going to tell Jack the next morning and was trying to find him but couldnt. Turns out Jack already found out and was ****ed. What my bf only told me recently was that he and Jack had previously had a convo where Jack said it was ok if my bf liked me / kissed me after the other night out as long as he told Jack. But even despite this to me it was unexpected how ****ef Jack was considering our thing had only lasted 1 week and it was many months ago. Since then Jack had things w other girls so i didnt think it would be an issue. A lot of **** happened from this where jack would go round chatting **** about my bf and how he kissed me and he basically ignored me and my bf for a long while despite being in the same group. Me and Jack finally had a converstaion and i felt bad for kissing his friend and i apologised a lot and he felt like i never liked him. I told him i did like him, but looking back i should have been compltetly honest and said i wasnt feeling it near the end and that i liked my bf. I didnt think he liked me that much as our thing was only for a week so i was surpised and felt bad and apologised. He still kinda ignored us and i drifted away from my bf bc of all this **** too. Eventually everything became fine but me and my bf never got together that year. I thought the timing was off and there were already too many problems / awkwardness in the group so i didnt think us being together would have been good. Fast forward more than a year we tried things again but Jack STILL had a problem with us being together and basically said he wouldnt be friends w my bf if we were together (they were living in the same house at the time). So again me and my bf j ended things.

A year later we got together again and acc stayed together till now. We didjt care what Jack said and it was fine we ended up not being friends with him for other reasons too but he didnt rly have a problem w us being together by that point.

Anyway my bf brings this up now and explains how unbelievably **** he felt that year thinkinng everyone was chatting **** about him and how everyone had the wrong idea of him when he didjt think he did anything wrong. Jack did tell a lot of people about this and probably did make my bf look bad. Esp as it was first year my bf was worried he wouldnt have friends after this or everyone would judge him badly and he said it made him kind of depressed. He said i shoukd have made it very clear to Jack and all our friends that i never cared for Jack and i didnt like him anymore and that what he and i had meant nothing and it was only for a week and that i liked my bf and wanted to be with him. He said the fact i apologised to Jack meant i regretted kissing my bf in the club. He feels very strongly he did nothing wrong. I dont think he did either. There was like 5 months between me and jack being a thing and me and my bf kissed and we really liked each other so he wasnt gonna push me away when i leaned for a kiss. He was also immediately gonna talk to Jack the next morning as well, and from what Jack previously told him he didjt think there would be a problem. I agree with my bf and have repeatedly apologised about not stabding up for him to Jack ever. I really should have and i know that but i also explain to him that i also felt **** that year and was worried about people judging me without knowing the whole story.

My bf hates Jack now and says that i never cared for him bc i let jack say all that stuff about him. And he always brings up the shower thing and i kind of feel Like my bf judges me for showering with Jack that quickly.

I have also done other wrong things like when it was my bf birthday in first year we camr back late and were gonna play some games in the common room. This was when the group was back to normal and Jack wasnt ignoring me or my bf. jack wanted to nap before playing games but everyoje said nah lets j play but he took my room key so i went up w him to nap. My bf was really upset by this and came w another friend to knock on my door to get us. I dont even remember this and feel so bad like i would never to anytbing like this ever now. I apologised a lot to my bf and told him i would never do thst now. Maybe i did it to be friejds again w Jack idek.

When going on a walk with another friend he asked me about Jaxk and first year and whether i acc liked him or not. I said i did like him yh. Bc i think i did at the beginning not like some mad feeling i barely knew him but i thought he was funny and yh ig i did a bit. That got back to my bf that i said that and he wqs upset i would ever say that.

I completely understand that my bf is upset i never stood up for him to Jack when i has opportunities to. Ig back then i was not a very confrontational person and i j wanted all the seams to die down. I’m four years older now and I’d like to think id do things very differently now but back then i didnt. We have had pretty horrific arguments with my boyfriend saying horrible things about mee which ik he doesnt mean but it still hurts to hear. i feel like i am some horrible person for acting like the way i did i j want some other perspective on this