After facing corruption in the porn industry, a film director and an aging actress teams up and kills those who is about to release their sex tape.

Perhaps the parishioner is blackmailing the lead character. She (or he) Tells the preacher the sex tape will be released if he doesn't give up a very large sum of money. (One Miiiiilion dollars)

The wife is all smiles and smooth talk on the set (A fictional version of TBN) but the moment the cameras stop rolling she is just mean to everyone including her husband and there is no way she is gonna let some hussy destroy their lives.

So she tells her husband in no uncertain terms to take care of it, and ask forgiveness later!

This leads the preacher down a dark path of blackmail, mobsters, and money.

The Twist: Perhaps the preachers ruthless wife was behind the blackmail the entire time.

At the end of the story, after he is caught trying or succeeding to kill the blackmailer. She comes out on camera crying and acting the victim, the movie ends with her in one-hundred percent control of the televangelism program and all the followers who watch the show feeling sorry for her. Donations go through the roof.

(She would not have gotten anything in a divorce because of a prenuptial agreement now she has everything)

This should fix some of the problems both 'dpg' and 'Mike Pedley' had with your story.

(The problem that no one would care about a sex tape in the porn industry. So, find a setting or industry where they would care if a sex tape was released)
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"When a famous evangelist discovers a video of him and one of his parishioners is about to be released, he and his ruthless wife will stop at nothing to stop the sex tape from being released and his career destroyed."

Possible Title: "The preacher in sheep's clothing."

Corruption in the porn industry is as shocking -- shocking!-- as there being gambling in Rick's casino in "Casablanca".

And what could possibly be scandalous about the release of a sex video in an anything-goes-with-anyone-and-nothing-left-to-the-imagine business of porn?