You have a severely twisted sense of justice. You see unsanctioned sex as worse than pre-meditated murder? What's your punishment when you catch your kid whacking off in the barn, amputation of his right hand?
And I don't see this as "justice." I see it as an artifact of tribal customs, something this woman and her lowlife "lover" knew well. They knew what they were risking -- they had been TOLD what would happen if the affair continued.
And Lothario was not exactly a choir boy. He was nothing but a tinhorn crook. I see this as two brothers from a primitive tribal village doing what the rest of the villagers didn't have the stomach for.
It's savage, brutal, and about as civilized as a stone axe. What it is NOT is "justice," nor did I ever claim it was. I don't care if they hang Bonga One and Two from the highest banyan in Punjab.