How does one discern the "leading of the Holy Spirit" - what objective measure for the validity of the "leading?"
I'm not sure how you discern for certain what is truth.
But I am almost positive that if you are being led to behavior that is in direct contradiction to the consistent, repeatedly stated, and never contradicted teachings of Holy Scripture that it is the "other" spirit, and not the Holy Spirit who is doing the leading. Both the Old and New Testaments are very clear that the only acceptable sexual behavior is within the bounds of a marriage between a man and a woman. Sexual behavior outside these bounds is repeatedly condemned in both the Old and the New Testaments. It does not make sense that a timeless all-knowing God would now suddenly contradict himself.
I am a pretty poor excuse for a Christian myself. But to try to swallow the doublespeak teachings of the Epsicopagans (my old Church) is enough to unchurch anybody. If the Bible does not say and mean what it clearly says, then the whole religion has no meaning. It is just a collapsing house of cards.