Happiest,
To repeat what others have said, even one case is one too many.
If there are indeed hundreds of cases (and the experts seemed to imply that it’s B”H not thousands), that’s hundreds too many.
However, “rampant” shouldn’t be defined by numbers, it makes more sense to be defined by percentages.
You indicated that you know a dozen or more victims (whom you met after you “started figuring things out for yourself”). This makes sense – people tend to seek out and find others with similar issues and experiences, but it’s not an indication of how widespread the problem is or isn’t.
I don’t think loshon hara or motzi shem ra on our entire community is justified, or even needed. I still agree, of course, that every reasonable step has to be taken to prevent even one more case from chas v’shalom occurring, no matter how rampant it is or isn’t.