AITAH for wanting to date my best friend’s boyfriend even though she likes me?

So I (15)F and my best friend also (15)F who we will name “A” have been best friends for around 6 months but have known each other since year seven so that’s three years (since I’m we’re in year ten), we are extremely close and although we are complete opposites we just understand each other on a completely different level and that’s why I feel so awful and guilty about my feelings for her bf, for context her bf, who we will call “S” is (15)M and also goes to our high school, she has known him for longer than me(for two more years), and I became HER friend first then I met him, and there friends “J” (15)M and “E”(15)trans, we will go into this more later but “J” was S’s best friend (at this time A and S weren’t dating) I knew that A had a big crush on S and I also liked S at this time but for the sake of my best friend I decided to ignore my feelings and help her get with him, which is exactly what I did, I asked S if he wanted to date A and after a lot of convincing he said…”yeah I guess” which at the time I thought was kinda rube but I also thought he was just trying to act cool and so they started dating, and for some MORE context A is bi, S is straight, J is straight, E is queer, and I’m a little confused honestly cause I’d say I’m straight but I act quite masculine, and as a female that makes me come across to other girls as lesbian or at least bi,and even though I’ve explained many times that I’m just a very understanding and safe person that doesn’t mean I’m bi,it just means I love everyone very much, sorry idk if that makes any sense 😭 anyways now I’ll get into the first big thing that happened.

A decided that once I got her and S got together that I needed someone as well, which I NEVER asked for but I went along with it as I wanted to get S out of my head so I thought maybe if I could get a new boy to like I’d stop crushing on S, well spoiler alert….it didn’t work, but none the less what happed was A decided as me and her were best friends and S and J were best friends too that she asked J who was also single if he liked me and he said yes eagerly….now I had nothing against J and I still don’t I think he’s a decent guy but as lauryn hill once said “some guys are only about that thing” and Jake was one of those guys and after I agreed to date him the next day at school he was very touchy and overly sweet , which put me on edge for some reason ..as I’m quite a small girl with blonde hair quite thin frame and which makes me quite a target, but what most people who aren’t close to me don’t know I’m veryyyyy much into stereotypical male things such as I’m a black belt in karate and I go boxing twice a week I’m into grime rap and most of these attributes are what make girls think I’m bi…anyways when I was touching up my makeup in a classroom I stayed behind in J walked in and shut the door…as I’d been feeling off with this relationship all day I kindly but firmly said I wasn’t looking to date anyone rn and I wanted to break up..he looked disappointed and almost angry that it lasted less then 24 hours….immediately this made my instincts kick in as he walked over and smoothly took my wrist and said “are you sure …we’ve barely been together yet”…and before I could punch the sh#t outta this guy, S walked in and said darkly…”J ,what are you doing” and he pulled him away instantly, this really surprised me as S is neverrr cold and is usually the funny light hearted kinda guy but this…was almost protective, which didn’t help my situation about trying to not have feelings for him 😭, J left and moved schools the next day conveniently as he got excepted to a full time drama school…honestly good riddance 😂, so yeah after that me and S became closer ..eg. Late night convos ,advice , I just tried to be a safe PLATONIC space for him and A even though it killed me on the inside.

But then…A and S started getting into loadsss of arguments and fights with each other, but the big problem was I was a outlet for both him and her as they were equally as important to me just one platonically and the other secretly romantically, this was really difficult as much as I loved A as a best friend she was really being a bitch to S for no reason eg here’s a typical petty argument..A:” I’m sooo stuffy inside, S please do something “…..S:”wanna go outside for a walk?”…..A:” NO I don’t how dare you!”…Me:”umm..want to go outside with me A?”….A:”Finally a good suggestion I’d love to “…Me and S: confused as f#ck.., anyways these arguments lead on for weeks until, one day as I was walking home alone with A, I was messing around as usual laughing then she took my glasses away so I couldn’t see (which I really mean I couldn’t see anything cause I am legally partially sighted) as she used this disability to kiss me over and over passionately..not a little peak but like..she was looking for something down my throat ..and I’ve been assaulted before by men…but I never even thought she’d try to..I mean this is the girl I told all my insecurities and secrets to..and she for one KNOWS I’ve had a past with being targeted sexually…yet she still did it and I ..froze and started crying..it’s stupid but I did and I didn’t know what to do apart from leave and go home,..so I did ..and it hurt sooo bad as I lay in bed at the situation…which which I thought of as a messy love triangle that I couldn’t escape ..

Fast forward to the holidays which is this week, and on Monday when me and him were on our nightly phone call, where I confessed my feelings for him, but said I understood that he liked my best friend and not me..which he denied and said he never liked her and instead loved me and just dated her cause I wanted him to…I know it was bad but I was so happy..we decided that it was a bad idea to date straight away but over the week we were saying “I love you” and “I trust you completely “ to each other regularly and were basically cheating over the phone…but it didn’t feel wrong to me as A also cheated secretly on him with me so I continued but told S I wouldn’t kiss him until he officially broke up with her when we get back to school on Monday…..tho the thing is…me, A, S and E are meeting up at E’s house on Sunday which will be the first time me and S have seen each other since we confessed on the phone….and he wants to..kiss but like I feel as if it’s to wrong …so I need some advice..would I be the asshole for wanting to date him after they break up or would I only be the asshole if I agree to kissing him on Sunday ..pls I know this is a bad situation but even criticism is good atp I just don’t wanna hurt them but I’ve been ignoring my feelings for months and I don’t think I can if I know they’re reciprocated by the one I love😭❤️.