Is quitting the best solution?

I shld be more cautious on what I gave to him and not intend to causing hurt.. because am not only act as nanny but as her aunt, I should be more alert and aware everything on him. I right to be put blame. I am should be responsible. I should tell the truth that I gave the weapon to him which cause his face got long scratch scar. But I cant. I just don't dare to admit these offence to his parents. Although being questioned few times, I only confess part of the story which not all true. If I admit thats my fault, what may happen? Of coz will be "teach" and "preach" till no face to put and probably giving me "red light" to stay away from his son although he is my nephew. I know the end result.. that's y I dont have the courage at all. 

The suspected weapon causing long scar

I should aware that stuff is harmful with sharp ends even though its only a biscuit packs. Every bend counts. every corner like sharp blade. But I thought if I gave him, then he wouldn't bother me eat my own biscuit. I don't know about it until I saw long scar at his face. He no sign of cry or even scream. He just stare at me and keep rubbing his face. By then,I only realize the serious case of this. The scratch will remain until he is grown up. It is very obvious part which just right after the eye. Even use plenty of aloe Vera still cannot cover it up. 

The baby with the scar

Handsome boy with long scratch scar mark.. So pity. Sorry boy.

Only so, I have to confess to his mother that he "in hurt". Something cause this happen but I dont know". At end, she says,"next time be more careful. Dont put him in playpen if cannot watch him. If really want, get something softer for him.". I admit that's kind of stern advice as a mother. If the child only 1 year and keep knocking here there, face no longer handsome, surely parents will worried and putting the blame on someone spent most of time with their child. 

This job is high responsibility. What I teach the child will showed how will he behaved. My bad tempered maybe will "given" to him. My aggressiveness may cause more trouble coz I cannot control my emotions to get angry. Sometimes he so cute but sometime so heart stricken actions. Is it the time to quit before more accidents happen? or should I tell the parents maybe I'm not suitable with this job? Is quitting can give me relieved?