First im only at episode 28 so dont spoil.

1 question: Why did Yu Wen Huai´s grandfather i think hes name is Yu Wen Xi kill all these women in the bathhouse?what was the purpose?

2. Why did Yu Wen Yue shoot Yan Xun ? was it to protect him? what reason?

3.  Does Yu Wen Yue know that Xing er heard his grandfather at this point? or does he just think she betrayed her? because it doesnt seem like he think she does hes just mourning her love it seems like

4. Who poisoned the princess food so that Yan xun got poisoned?

1) He's just a sick old grandpa and that was how he gets his entertainment is playing with and eventually killing the maids around him.

2) If you're talking about when Yan Xun and Chu Qiao are escaping and then get captured, it actually wasn't YWY who shoots them, but his grandfather's assistant who shoots the ice arrow to make people think it was YWY.

3) I don't think he realizes that she overheard them until the night that she takes revenge on the Third Branch grandfather.

4) Not sure who specifically poisoned the food, but I think it was plotted by Wei Shu You 

Hi i wrote you a personal message but you havent answered, I am at episode 58 now i think, I have a question Before xan xun fired that arrow to kill yuwen yu he thought to himself that achu told him that he hasnt changed what his goal are. But i didnt get what he ment with that did it mean this was what he wanted all along and hid it to her? or was it the goal was her? and he felt he didnt have her cause her heart belong to someone else?