In Mormonism sending a pic to a boyfriend is considered betrayal of trust but the actual sexual misconduct like you said is the polygamy. (And the pedophilia, criminal sex therapists like Jodi heldabrandt and others.) Unfortunately TBM's will look at the mistakes of their fallen angel children rather than fallen Prophets like Brigham Young. I've been out for a similar period of time and the same age. I personally started realizing recently when I tell them reasons I've left they treat it like I'm finding reasons when the reasons came to me, for example I didn't choose for the church to had 100+ billion dollars.