Wife's EA with Stepbrother...Expose to Family vs. Don't Ask Family for Help per 180

I don't really suppose that my story is outrageously unique, and I'm working on putting my "full story" out there, but I have a specific question which I don't necessarily know requires the whole screenplay yet be completed. My wife has been involved with an on-again/off-again EA with her stepbrother over (at the very least) the past 6 years, though I suspect it is considerably longer based on what information surfaced after D-Day #1. In fact, for longer than I even know her. She came with this baggage, and I hadn't any indication prior. We're both in early 40s (married 5 years), and since I have hard evidence, I have been considering exposing the relationship to the parents, as I've been sitting on this for the aforementioned length of time and a recent discovery resulted in the reopening of wounds I thought were closed/closing. I am certain that it would mortify my MIL and "StepFIL", but I know it would likely piss all over whatever fire it is my wife and her stepbrother think keeps their involvement hot, and I know it would cause a likely incurable resentment against me on the part of my wife (not that I would accept any guilt for having done it). I've read that exposure of the EA is important, but what I've read seems to center around OMWs or OWHs. This is a different dynamic, and I also understand that the tenets of the "180" dictate that you don't ask the family members for help. Unfortunately, exposing the EA to the parents is tantamount to asking them for help in quashing it. I'm confused and would appreciate whatever thoughts people would care to share on this situation. Thanks in advance. Hopefully, this is at least moderately coherent.

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