the very core of LDS eternal truth and my belief system, I would rethink my beliefs that revelation ever came to any prophet in the church at any time.

I don't doubt that being gay is a trial that some may have to go though on this earth to gain the growth they need to become like God, but same sex couples being married in the temple for time and eternity is contrary to the very essence of the plan.

At that point I would believe that JS made the whole thing up. Continuing revelation is important to the church, but it is not a "core, eternal truth".

Continuing revelation as come and gone throughout the ages as it stands anyway.