Your Fatal Fantasy
You found "the one who got away" on Facebook. I trusted you to be sane about it. You started buying her things and spending time with her, helping her with her innumerable crises, leading up to the day you told me, "I love her."
Why would you throw away 20 years of a happy, strong relationship and a solid life together for a bullshit fantasy? She has not been there for 20 years to take care of you, to listen to you, to understand you, to share VOWS with you, and to accept you AS YOU ARE and not as some savior. She is not real. What you have with her is not real. It is fantasy and it is poison for everyone involved. The smartest thing you could do would be to cut off contact, but you say no—"It hurts too much."
You won't even commit to us trying to stay together, just to "figuring out what you want." I feel like you are only hoping that you come out of this at the other end with permission to be with her, and that I will be okay with that and let you go off to be happy.
I am not going to let you do this to us. I am being as understanding as I can, but I cannot sit by and allow you to tear our lives apart. You need someone to stop being understanding and tell you to stop what you are doing before you ruin the lives of at least three people.