is this my fault (long adhd)

I NEED TO SETTLE THIS. I always thought it was my fault and i blamed myself and when i moved away i felt like i wasn’t really at fault as much as i thought i was.

so basically there was this guy who was in a relationship with my ex best friend. this girl and i ever really talked unless we were in person but it was never anything deep, we stopped being friends in like middle school and each had our own friendships and relationships without each other. Anyways this guy and i became really good friends in my junior year, i thought we were best friends, and he was my rock when i was breaking up with a different guy. he started telling me during my senior year, i remember it was the end of December because he had gone home for Christmas break, that he and my ex best friend (they’d been dating for a year) are fighting a lot, he doesn’t feel that connection with her anymore because of the fighting and he wants to end things but he’s scared he’ll lose his friends because he met them through her. he began telling me they’re fighting. during that time i heard a rumor that he cheated on her but when he knew i found out he called me and like started crying being like this girl idk why she’s doing this it’s not true and so idk why i believed him i kinda should’ve seen the flags but hindsight is 20/20 so. he told me in february that they’re going through this cycle of being good, fighting, and the breaking up, then reconciling.

he told me they broke up in april of that year, and he proceeded to begin flirting with me, we intimately texted. (talking about a “i’ve liked you this whole time i just couldn’t tell u) two days later she posts a picture of both of them. i immediately text it to him like what the fuck? he says they got back together. i said i don’t feel comfortable with this and he said “we’ll just put a pin in it” and i was like like um ok?

a couple of days later he was like my friends were like going on my ass about it so we got back together and i was like hm what and he was like apologizing and saying like he’s actually done with her and like just said things that like now are such red flags but i honestly really liked him so i just went along with it. it happens again and then again she posts a picture of them i tell him i want to tell her and at this point i had been sweating for days, i felt like something was off and i felt so guilty for it so i told him i want to tell her. he began crying and even brought an inhaler manipulating the fuck out of me. i was like ok but u have to tell her. one of my friends figured it out and so i just told him i was telling her and i told her everything. she blamed me for the whole thing and is now friends with him.

i’ve always felt really bad about this, i’ve apologized to her 3 times. this is the biggest guilt i have and idk if i am really solely to blame.