I guess that's also a form of revenge. He is going to die tortured by the fact that he let the one person who understood him and cared for him sincerely die and betrayed her.
That after all that he has done while his wife was alive, she knew and has forgiven him. The guilt and the pain from losing someone like that and even betraying that trust and devotion. I can see it as a form of torture. Plus he is going to die because he'll keep on uselessly apologizing and die without food and water.
Raoul's sister was actually an angel. Oh my god.
The amount of respect he has for her to even consider not taking revenge on someone his sister cared about but ultimately betrayed. Fuck this shit is heavy.