<human>: Basically, my wife[26F] and myself[27M] have been together for 6 years now. We've had our ups and downs during our time, but we've managed to remain strong despite everything ( normal relationship baggage). 
However, my wife recently met a coworker[F] who has basically acted as a catalyst for my wife to plunge into some dark behavior ( drug usage, lesbian tendencies). My wife is not a lesbian, she merely has strong sexual desires. 
This coworker is a swinger along with her husband, so my wife expressed interest in the idea.
I am completely against it, and we have talked extensively about it. However, whenever we make some ground, we seem to take 3 steps back, because when she interacts with this coworker again, they fall back into their user patterns, treating sex and drugs as, well, a drug.
I've tried to be supportive ( as much as I can ) while attempting not to enable, but it feels like the strain is becoming too much for me. What advice could anyone offer to stop a major rift from occurring between my wife and I which could lead to, undoubtedly, a divorce?

Can you give me a shortened version of the text?
<bot>: wife wants to swing and heavily use drugs because of new coworker she met, and I do not want to go down that road while keeping the relationship intact.