CW: Mentions of Suicide and Self-harm

Hi everyone! I hope you are having a good day. I met this very nice girl in my college, we started talking and we had chemistry, but she warned that she had BPD, I appreciate her telling me that and trusting me enough with that information, but yesterday, around 1am she started feeling really bad. She started asking me if I ever had a suicide attempt or if I had cut myself (to be fair, I had, I do have depression), but I wondered why she was asking me this, so I asked her the same questions, she started telling me about her suicide attempts and previous self-harm, and I started to suspect that she was having suicide ideations, I offered help but she joked it away or simply said "If I do something, I want to do it myself". I stayed awake until I was sure she had fallen asleep and was safe until tomorrow.This didn't annoy me, of course, but it preoccupied me, even if I just met her some weeks ago, I truly want to help her, for who she is, I don't care if we end up in a relationship, I just want her to be safe. This is my question, how could I help her? Is there something I should expect and know how to react to? any help or information is welcome, thanks to you all.