I am suspicious of my bro's wife fucking her sister's husband .( (with her sis consent) ( I have some strong circumstantial evidences against them but I am not 100 percent sure).

My bro's wife is extremely slutty and is fucking one another guy ( I am 100 percent sure about this guy as I have photo evidence )

Is there anything that I can decode from their body language or personality like some contradictory behavior or something like that.

Her sis's husband acts like extremely extremely nice guy . I have never seen a nice guy like him in my life , but I am doubtful that he is just acting so that no one will be suspicous of them .

But her sis's husband is also a surgeon . This is what I find contradiction in his personality .( Surgeons must be sociopath or else they will not be able to perform surgery ).

Also once I saw him meeting one of his female collegaue , but he didn't act nice with her .

I am suspicious that he acts nice only infront of our family so that no one can doubt him.