Well. I think there's a few levels to that.
First, recognize she's probably giving people the best advice she knows to give. That doesn't mean it's always correct. That's why it's called advice. Nobody is right 100% of the time. I've counseled people to euthanize a dog, had them refuse, and subsequently seen the dog treated back to health; most recently with a HORRIFIC necrotizing and infected injury covering most of the dog's right side. *shrug* Sometimes advice just doesn't play out. So maybe cut her some slack for doing the best she can?
Second, have you tried just.... yanno.... sending her mail and explaining your personal experience? Explain that hey, you advised me that I couldn't get into vet school, and I was able to get in, so maybe reconsider how you are advising people? Nothing wrong with a direct approach. Easy enough to be kind about it and just say "Hey, as feedback....."
Third, is it really your job to repair her "damage"? Not meant in a snarky way. Just.... focus on things you control and are supposed to be responsible for. Don't stress over the rest. Yanno?