how do you survive this?

a dear friend of mine is suffering. he is suffering with probably the biggest humiliation of his life. horribly mortified. let me tell you the story.
he is a grown man, late 40's, with 5 teenagers. 4 boys and a girl. the girl is the oldest at 18 years old. she is a nice girl, beautiful, but doesnt date. she is focused on school and her parents(now amicable after a nasty divorce 10 years ago)speculate that their divorce made her leery of getting involved in any romantic entanglements.
my friend has dated quite a bit in the last 10 years. he has had a few relationships and two short lived engagements. from what i can piece together, it seems like it was always something with the kids that ran the relationship off the tracks.
about 8 months ago he met the love of his life. i can tell just by the way he talks about her that she is THE ONE. i am envious of the relationship he describes with her. it sounds truly amazing.
they have had their ups and downs. a good portion of their relationship has been long distance. they talk regularly, but like we all do, rely on email and text messaging for communication.
just recently, they were flirting big time via text. it started going into rated r territory when by some bizarre cell phone catastrophe he sent a naughty message intended for his soul mate to his 18 year old daughter.
yes folks. his pg-13(ok maybe r)fantasy was transmitted to his young daughter. he is mortified. we spoke briefly and he is shock, so embarrassed, and inconsolable.
from what he tells me, his daughter is judging him pretty harshly.
i agree that this was a mistake. he and his girlfriend should have never allowed their texting to go that far, but as embarrassing as it might be, he is an adult, and to me, he should apologize to his daughter for the mistake, but explain that its none of her business.
am i crazy?
ps-all the people involved in this story are lds. active. my friend and his girlfriend have temple recommends.
pps-he sent me the text so i could see exactly what it said-it was mainly kissing stuff(the silly stuff we say to each other when we are in love)-which would be embarrassing to any kid- but at the end there was a reference to untying a bathing suit top. should he be burned at the stake? i am thinking no, but...