AIO for getting upset because of my friend going to a party where someone she has a case against was there?

For context, I am a college student in the UK. I am a teenager, I only have a provisional license. None of the people involved are legal adults. I don't go to the same college as my friend who is a few months older than me. However, my friend is, as mean as if sounds, a complete pushover. She went back to a toxic online discord ex even though I reported him for sending nudes to her (he was 18, she was 16.). And she doesn't listen to advice despite asking for it and crying about it. I've known her for almost six years. I'll name her Emily.

This whole thing started a few weeks ago before the end of the academic year. Emily does photography in her college and has made some friends within her first year at this course. One of her friends, Holly, has a boyfriend. Who is a massive prick. This boyfriend, Matthew, has been recorded by the college for harassment once before since he spread ai videos about someone else in the college. A few weeks ago, Matthew made up a lie about Emily about how she was dating someone and told the guy she was talking to about it, WHO IN FACT, was the guy that Matthew harassed with AI hate videos a few months prior. This caused Emily and the other boy to obviously have an awkward falling out before they found out it was a straight up malicious lie!!! A few days later this Matthew began messaging Emily on Snapchat after Emily told Holly about Matthews behaviour. These messages consisted of constant name calling such as 'slag' and 'bitch'. This went on for TWO DAYS. Emily didn't at all block this Matthew because she 'wanted to see what else he'd say' before we eventually got her to report it after Matthew ended a conversation on Snapchat with a comment about Emily leaving her new boy behind and going to be bent over by the ex I mentioned earlier. (Same ex that groomed her and emotionally abused her). After this she reported Matthew to their college, and to the police. Both of them telling her to block and avoid Matthew.

Then emily was reminded that the same Matthew was going to a birthday party of her classmate, (a party she didn't HAVE to go to, she only went cause of ALCOHOL, that was what she was excited abouf). I told her not to go unless Matthew wasn't going. She didn't tell me UNTIL she was at the party that this Matthew was there. Now I've been involved in police cases before, I know how someone can instantly turn your 'im afraid to be around you!' statement with a simple 'we went out together after the report!'. Obviously I was pissed. I had just dealt with her stressing and crying about this bullying just for her to go to a party where there would be THE GUY SHE HAS AN OPEN CASE AGAINST AND ALCOHOL IN THE MIX. She had literally been with me earlier that same week helping my dad since he had to go to hospital. She knows I am a stressy person and I am protective of 'my people'.

I then find out, when I woke up, she only got home at 3:45 am. And when I spoke to her about Matthew she said "oh I avoided him." Then she proceeded to say "I only spoke to him to ask about Holly". I genuinely started seething. What do you mean you are told to avoid someone by the POLICE and you go UP TO THAT PERSON and SPEAK with them DIRECTLY. I was like "so you interacted with him despite being told not to 😐". And she had the AUDACITY to say "to make sure my friend was okay..?".

Keep in mind, this holly girl has DONE nothing about the abuse her boyfriend has been giving Emily. I don't know why Emily is friends with this girl, they've only known each other for less then a year and clearly this holly doesn't care. Oh, and it gets worse!! Emily, spent most of the night with the girl she DIDNT LIKE. Make it make sense.

I was going to tell her to not come to me or our friends crying about being harassed if she was going to be an idiot and actively engage with the harasser, but I chose not to. Am I overreacting?