May I ask you to use spoiler tags when you're really saying something very, well, spoilery? Thanks!
Actually, if you think about it, Divinity games never really ended positively.
In the first Divinity, you cannot really stop the bad guys from summoning the ultimate evil into the child. You cannot get yourself to kill a mere baby even though you know it is ultimately evil.
In Beyond Divinity, you find out that in the end, you have helped Damian escape all this time, and he even casts you (the player) back into Hell.
I know this doesn't change the way you feel or it doesn't change the ending. You are indeed a mere pawn in the history of Rivellon, but in all cases a very important pawn: without the player in Div1, Damian would never have existed. Without the player in Beyond, Damian would never have escaped from Hell. Without the player in Div2, Damian would never have been reunited with his loved one and gotten even stronger. It is an important part of the story that needs to be told.
You _are_ writing and experiencing the story, and you have been a main character in the history of Rivellon. Your name will be known forever. Hailed or cursed. If this were a book, you may have felt differently about the ending.
I am not trying to "defend" the story, this is how I interpret it. I could also go philosophical and talk about the never-ending struggle against evil that cannot simply be fought and ended by one man only, but that would be taking it too far perhaps