I hate to say this and I'll be a lone voice, but I agree with
@Twilight Hue. When I was a teenage boy, I and my friends thought of little else but sex. There was very little actual sex going on, largely because it was before the days of available safe effective contraception and the girls naturally avoided the risk of getting pregnant. But there was a lot of sexual activity going on that stopped short of penetration. So for all the boys that claimed sexual experiences, most of them made it up. I am very sure that a boy who actually had sex with an older woman would be universally envied and admired. I can't see that such a boy would be harmed mentally, though obviously STDs were not fun in the days before effective cures.
Add to that, the "age of consent" was 16. It was in England. I still smile when I hear a sexually mature 17 year old girl being described as a "child".
OK, that's not a teacher's job and this woman shouldn't have done what she did.
I do think though, and I won't be agreed with, that the current way of starting sex is not a good one. Typically, clumsy untaught boys try to mate with untaught girls and often cause them pain. Both are then put off and a bad start is had by all. I don't see why sex shouldn't be taught as a practical subject, just as we have driver's ed.