The Obsessive Devotion Lyrics

Lyric discussion by Niels 

Cover art for The Obsessive Devotion lyrics by Epica

I'm not sure about this, but I think the Latin means this:

Fortuna exprimitur artibus falsis et mendacem memorem esse oportet = Fate is enforced by misleading tricks and one must be aware of the lie

Adoratio permanebit. Quotiens me eges, adero = Adoration will continue its existance. As long as you long for me, I will appear

Venia ad vitam aeternam, non mihi, non tibi, sed nobis = Come to the eternal victory, not for me, not for you, but for us

Fortuna mutual coniuncti per tota saecula future = Borrowed destiny and future generation are fully interconnected

Venia ad vitam aeternam = Come to the eternal victory

As others said, the song is about not being able to leave the one you love and hate at the same time.