Tw: SA, Self harm

So my cousin (13F) and I (25F) have gotten close since her dad, my uncle, died. She added me on tiktok a few months ago and I assumed her mother knew.

Recently she's been posting concerning things. Mostly self harm allusions, or talking about her low self esteem.

Last week I called my aunt (40sF) and told her that her daughter is posting these things and she didn't even know my cousin made a tiktok! I told her I think my cousin should get therapy and to keep me anonymous when she talks to my cousin.

We went out to dinner this weekend and my cousin mentioned her tiktok in passing. So I assumed they talked about it.

She is still posting about her self harm. No photos but reposting videos on that topic.

Tonight I hit my limit. She made a tiktok saying when she was 8, a 12 year old female cousin molested her as experimentation. Idk why but I am like actually mad bc I told my aunt I suspected my cousin was sexually assaulted but she said there was no way.

So I took a screenshot and sent it to my aunt saying "(Cousin) posted something publicly that is again concerning. She's implied a female cousin sexually assaulted her when she was 8. And this is set to public so anyone can see. I made sure to take a screenshot this time so you could actually see what she said instead of me quoting her"

I sent that text 15 mins ago but immediately felt guilty. I feel like I'm betraying my cousin because she trusts me. I remember being a teenager unmonitored on the internet and venting anywhere I could. Should I have messaged my cousin first? Why did I tattle on her and not offer support?! I've turned into someone who I would have hated at her age.

I'm also scared my aunt is gonna get pissed at me for bothering her with this if she already talked to my cousin last week. I'm scared my aunt just doesn't care, but she seemed to take my concerns seriously on the phone last week.

AITA? What should I have done better? Am I right for telling my aunt about her daughters tiktok?