Based translator on /fgog/ translated a bunch of stuff from the UBW bonus novel
Ctrl-F Garden of Avalon for it
>-Lancelot had heard rumours of King Arthur from across the sea, but pretended not to be interested because he thought of himself as the ideal knight, and headed to Britain in the first place because he didn't like how he was being compared to him.
>-Lancelot claims that Agravain knew Artoria was a woman, and that he was using her and threatening and insulting Guinevere, and that's his reason for killing everyone for no reason.
>-Lancelot says that he's an adulterous traitor and a disgusting beast not even fit to call himself a knight, and when he learns that King Arthur forgave him, his first thought is that this is because he's so important and great that Camelot would collapse without him, though he dismisses this saying that Arthur would never be so calculative. He doesn't understand this decision and comes to the conclusion that Arthur is inhuman and is a bigger monster than Vortigern the likes of whichno human can hope to understand. He still respects the king but is also angry and cannot accept Arthur as a human. He thinks his fear will someday turn to rage, then hate, that will curse the king for all eternity, and figures that this is his punishment.