Ah it's different from what I originally assumed

https://scholar.smu.edu/cgi/viewcontent.cgi?article=4072&context=smulr

(See page 509)

• knowledge isn't necessary, just assumptions

• "need not be committed while in the heat of passion"

• "The statute also uses the phrase "before the parties ... have separated." This has been interpreted to mean only that the parties are still in each other's company, not that they are still united in the act of copulation"

• "while the husband may justifiably kill his wife's paramour," he may not [...] inflict serious bodily injury (mutulation) upon the paramour without an intent to kill"

• "Further, the wife is not justified in taking the life of her husband's mistress"