Which is worse? talking to your ex behind you partner or blabbing your partner's secret to others?

sorry if the question was too long. uhmm.. my girlfriend had this boy his name's kyle. he was kinda special to her. they liked each other a lot. suddenly, kyle just stopped being sweet to her. then kyle said that he needs to prioritize badminton first and stuff. after a few days, kyle tells my girlfriend that he's gonna court this other girl. so for my girlfriend, kyle just didnt want her anymore. they never had any closure. just recently, there is another boy whom i think is flirting with my girlfriend. a few weeks before this, i heard from my girl that this boy wanted to slow dancewith her. but my girlfriend told me not to tell anyone. i got so pissed i talked to the guy. i told him about that slow dancing thing and my girl got so mad at me for telling. she said she doesnt trust me anymore. then out of nowhere, she tells me she talked to kyle. ive told her all the time not to cos he hurt her so much. but she still did. so which is worse? me or her?