What else you could have done? Let her make her own choices. It's not your job to intervene. You can make her aware and let her make an informed decision. You don't have to like her choices and people need to sometimes make mistakes to learn from that and grow.

I truly hope you will too but so far I mostly read from you: Yeah I fucked up and then a justification.

Good intentions do NOT justify the means. You did see " red flags" and became the red flag.