Is it a 'sin' to be an adulterer; iffn you only THINK about it?
One can be an "alcoholic" but not a drunk. I know alcoholics who have been clean and sober for years. They're still alcoholics, though. Same as a chaste, pure, God-pleasing person whose unbidden sexual attractions are for people of the same sex. Still homosexual in orientation, but not rolling out the welcome mat--- or the sofa-bed--- in his mind!
“Is it a ‘sin’ to be an adulterer; iffn you only THINK about it?”
Yes. Thinking LUSTFULLY about a sex act is just as sinful as actually doing it. And self-abuse is a sin just as mortal as adultery or rape. The Roman Catholic theology is that any intentional sexual release, OR willful thoughts that could incline one that way, outside of man/woman marriage, condemns one to Hell for eternity.