It's been defined by one far greater than I:
"And he saith unto them, Whosoever shall put away his wife, and marry another, committeth adultery against her.
And if a woman shall put away her husband, and be married to another, she committeth adultery." - Mark 10: 11-12
2) Look for that definition in your quote.
Nowhere does it mention divorce and remarriage.
3) Report your findings.
Consider them reported.
You missed, from your very own quote, "heterosexual activity outside of marriage". Go back, reread your quote, see where it is.
Comments?