@Goyal99Raj She does feel guilty over it. She states it herself too. However, her opinion doesn't really matter Nine's view of the situation is all that actually matters. Even if he's being used for her own motives he doesn't mind plus, she totally is paying him a ton of cash to do it.
If i recall correctly from the novel he has part of his tongue still. Which is why he can still enjoy food, but he can't really use it to make the words he needs..also i think they made him mute by doing something to his vocal cords or something