"Nevertheless you, O Sir Gauwaine, lie, Whatever may have happened through these years, God knows I speak truth, saying that you lie."
After that long, hypothetical "what-if" scenario in which the
speaker asked the "knights and lords" to imagine having to choose
between heaven and hell with no information to go on, she interrupts
herself.
Even though she was afraid, for some reason, of dying
after Launcelot left, she insists that Gauwaine is lying, and God knows
it.
Does that name ring any bells? Gauwaine (or Gawain) was also
one of King Arthur's famous knights. Maybe you've even read the old
story Sir Gawain and the Green Knight.