Avoid the days of PC....I could just give you a kiss. Such good advice. (a Lil of tough love) Please pardon me...You could ask her to cite her research sources - bet she won't, but it might shut her up (probably not). It's a tough call whether you want to wrangle with this person or not. On the one hand, you probably want to just slap her; on the other, you despair that you'll ever get her to change. Unfortunately, it's the animals who suffer. The best you can hope for is that someone looking at your post will think twice about what you've said and come here.
If you decide not to take her on, I wouldn't blame you one bit. If you do go for it, ask yourself "What's the worst that could happen?" and prepare for that - anything else you can handle. Good luck!