3 entities involved:

Entity A - consulting business I own
Entity B - multi-time client. (Tangent: owned by an LDS guy, and I’m LDS and my team is well aware of this)
Entity C - company that I also do some work with

So B and C have had a business relationship for a decade, which precedes my relationship with either of them, that deal is massively skewed to the benefit of Entity C. This makes entity B super angry and feeling as if being taken advantage of - but honestly due to market forces Entity B can’t get out if it.

Unfortunately Entity B has chosen to get back at “C” by committing fraud - which I’ve now become aware of. My educated guess is several million dollars worth.

“B” justifies this as “just trying to get what would be fair” and feels like even with having done so “C” still has an overly advantageous deal.

Terminating relationship with B and just keeping quiet to C doesn’t feel right.
Turning in B and all the subsequent trauma for “B”s” family and the employees of “B” isn’t an idea I like even though B’s actions disgust me.
Letting B continue committing fraud also is the wrong thing. (I am going to end relationship with B regardless because I want no association with those actions)


What would you do, or be thinking?