My sister is planning to attempt

I (21F) came across some concerning posts from my sister’s social media that she reposted that expresses plans to harm herself. She recently broke up with her boyfriend and she’s 14. She did recently start therapy a couple months ago and from what she told me it was due to depression and anxiety, so I have been aware she has been struggling with mental health.

I myself am no stranger to mental health struggles, I suffered from severe depression at the age of 12, later being diagnosed with bipolar disorder at 14 and borderline personality disorder at 18. We are half siblings who don’t share the same father, I grew up with a very abusive narcissistic dad so it was very hard for me to form close meaningful relationships with others which caused a rift in my ability to bond with my siblings growing up. 3 years back we all started building relationships with one another so our status is good, however it’s still hard for me to show affection and personality at times. But they do know I love and care for them.

I’m trying to figure out how to approach my sister about this, because I am concerned for her safety. I don’t think it’s right to wait for an attempt to happen to have a serious talk about the suicidal ideation she’s been having and sharing online. I meant to bring it up yesterday, but I wanted to approach it in a sensible and appropriate way that doesn’t make her feel judged or attacked. I feel like it will be an uncomfortable topic either way, but it has to be done. I plan on talking to her about it in person privately after I get off work. I’m trying to do it quickly since one of the concerning posts involved a nearby date for when she would attempt. Looking in as an adult on a depressed 14 year old is so different compared to I was a depressed 14 year old myself. I don’t know the proper things to say because the things adults told me at the time weren’t the things they should’ve said.

I’ve been banker acted in my adolescence a couple of times and I know it is not a fun experience at all, kind of traumatizing honestly. But it did save my life on multiple occasions. If it gets to a point I am genuinely scared for her safety and have to call authorities, I would feel so much guilt. She is home alone most of the times because our parents work and I live separately from them. That will not be my first route of course, or at least I hope it won’t have to be. I will have the talk with her and see where we stand, and either way I feel mandated to report this to my mom and stepdad so they can alert her therapist. My parents are good when it comes to understanding mental health, however there is a language barrier so my sister tends to not to open up to them as much as she will open up to me sometimes. Any advice and thoughts? Mainly on how to go about talking with her and what to do if it gets to a point. I’m very concerned and at a lost here