The Unhappy?
Faithful I - Well, he was faithful till the kidnapping
yet I my lord betrayed - for sake of his wife
To serve the one who wielded shadow - Sauron,sort of
Shadow I helped defeat. - He warned the son of his lord of incoming danger; also, were it not for his treachery, the biggest couple of First age may not have met each other and Silmaril would still be with Morgoth
Patient was I - He always returned to check on his wife
but rash move I made. - One day, he heard her calling, rushed to see her and thus was captured etc.
Madness tore me - Grief for his wife
now at last I
Know what it is to sleep. - died
I explained all the lines!
