Is OTHER wrong in the post ? POST : So this is a long post, TL;DR at the bottom

I've known this girl for several years now, I found out back in July 2018 that she was going behind her boyfriends back, talking shit about him, comparing him to her ex in everything he did, she even sent me a screenshot of a conversation between her and some other guy, basically them flirting. I didn't say anything about this to her, thinking it wasn't my place to get involved. 

Maybe a week or 2 after that, her boyfriend found messages on her laptop (unintentionally) to several other guys that she's been texting and flirting with behind his back. This obviously upset the guy, so he came to my S/O and told him about all this. My partner came to me, and told me about this, because seeing as she's my friend, I should try and talk to her. I confronted her and she went to her boyfriend, and started giving him shit for going to my S/O and "spreading gossip".

Somehow, me and my partner turned out to be the cause of they argument, which we weren't keen on being involved in in the first place. And we lost touch for most of the summer.

When I came back to university in September, my friend and I briefly met up with another mutual friend of ours, we seemed to talk it out, and come to the conclusion that what happened during the summer wasn't anyone's fault and it was just a big misunderstanding where everyone ended up getting heated and overreacting. This was fine, we ended up talking and stuff again, seemed like everything was behind us.

Recently we met up again, she had a few drinks and accidentally let it slip to us that she was planning to break up with her boyfriend after she finds her own place to move into, because she "doesn't see it going anywhere" .. "he's just not (her ex's name).."I just need a place to stay at the moment and have nowhere else to go". This surpised and shocked me, and I asked her is she sure she wants to break up because them two seem to work so well.

At the end of the night, I came home to my partner and tell him about this as it was kind of concerning me. He told me that he was thinking of just going to her boyfriend and telling him about this, as she is just using him and it isn't fair on the guy. I thought it was the right thing to do, so I ended up texting my friend and gave her a heads up. Basically saying "hey look, I told my S/O about what you said, with all the breaking up and stuff, sorry, I know it wasn't my place, but it didn't seem fair" she then came at me saying that she had never said that she was definitely going to break up with him (she did), etc. And that now she's gonna have to deal with that, thanks a lot.
My partner didn't even bother contacting the guy anyway though. 

I dismissed these as I knew she had a few drinks earlier that night, but she texted me the next day saying that I've always been a horrible friend, and that I only ever met up with her and our other friend to get the gossip, and then "report back to your keeper" which I found absurt and laughable to be honest.

I have since stopped talking to her, blocked her on social media. I did see her a couple of days ago and we exchanged a few words, in which she informed me that she has in fact broken up with her boyfriend and that she has found a new place to live in, etc. I'm just not sure if I was an asshole in this, telling my boyfriend in confidence something that was bothering me.

TL;DR: ex friend was using her boyfriend, his money, car, house, etc. She was planning to break up with him as soon as she had backup, and told me this. I told my S/O about this as he is friends with her boyfriend. He wanted to text him to warn him, I talked him out of it, but still told my friend that I had told him. She flipped out and started insulting me saying that I can't keep my mouth shut