If the time isn't right for her to tell her husband, it's not the right time to date her. You love her, have feelings for each other, but you have already 'waited' 14 years. You and she can wait a little longer. I suggest telling her you love her, you will still be in her life, but you will not date her until she has talked things over with her husband explicitly.
I fear she is never going to find 'the right time' to tell her husband but it would be nice to be wrong.