yes it has to be a terrible breach of trust between parent and child. And deprogramming seems to me to be such a horrible method. Forcing you to change your beliefs? sorta puts you at odds with yourself just as much as getting the religion in the first place did. Even if it's successful it's put you in a double bind.
It reminds me of the next thing that came up to change people's minds - hypnotherapy. That's still a coercive technique and an irritant to the soul.
I saw this movie and at the start of it a man is having this terrible nightmare with grey billowing smoke and the end of the world. Turns out this is the nightmare implanted by the hypnotherapist should he light up a cigarette. He quits smoking.
At the end of the movie which I can't remember what it was about, he takes up smoking again. The only way back out of the nightmare is to face it up and dispel the hypnotherapy programming.
The good thing I guess, that you can take out of your parent's actions is that they went to such lengths to get you back.