She obviously knows it's wrong if she lied to you about their conditions. No offense, but she sounds like a very bad person if she knows what she's doing is wrong.
You could try to get her to join this site maybe. Not like, "You should join this site so you can see that you're treating your fish wrong." Just say something like, "I've found bettafish.com to be a really helpful tool, and it's a great community." Or say anything that will interest her to join- the positives rather than sounding negative.
Techno- Red VT male
Peanut Butter- Cambodian red CT female
Mr. Brightside- Multi salamander HM male
Nemo- Purple salamander PK male (with a special fin!)
RIP Charlie, Flame, Indigo, Juliet, St. Jimmy, Reese, and Temeraire
<3 Dented Personality, my band.