Think an old partner (20F) lied about their age to me (23M)

Bit of context here, in 2017 I (16M at the time) met this girl over AO3 and clicked immediately. We were part of a larger group in our community, however we had the best connection. We were in the same year in school and we spoke about everything, from our GCSEs to family issues and just venting in general etc – from what I gathered she had a rough home life: her dad was absent, she had recurring cancer and suffered from severe depression. She was, to my socially inept sheltered teen self, one of the nicest and funniest people I’d met, and it felt nice at the time to have someone that treated me like a human being.

We got together about six months after, and her entire personality switched. She demanded to know my location 24/7, controlled who I spoke to and what I could and couldn’t write, told me who I could and couldn’t be friends with, and was overall very emotionally manipulative, even going as far as to lie about cheating on me the first day of sixth form we had. I broke it off at the end of the year, but when I tried to speak to the others they said they had been told by her not to talk to me. Bit weird, but didn’t think too much of it.

Fast forward to about a month ago, and I saw a local news report that had what I thought was her in there. The name and area matched, but the age was off – instead of being 23 which would match up with her saying she was 16 at the time I was with her, it said she was 20, meaning that at the time she would’ve been 13. I haven’t been able to find it since, or any other mention of her age, and it’s driving me insane.

I feel so sick and disgusted with myself that I was potentially with someone who lied about their age to get with me, and I don’t know what to do. Looking back at it now the signs were there, and I’m so fucking pissed with myself that I didn’t see anything at the time. I’m barely sleeping, I can’t bring myself to eat, I’ve dropped out of college as I don’t really see any future for myself now. The only saving grace is that I was able to log back into my account from ages ago and screen record the messages where she’d told me she was 16, along with other supporting evidence like her talking about her GCSE results and what A levels she was going to do.

What do I do now? I don’t know what I do with life. I don’t know if she was even real, or if I was being catfished. I feel like an absolute piece of shit, and I can’t stop worrying that I’ve destroyed her life with this.