That Shadow That Haunts Me

On a bright not so happening sunday afternoon,i did a terrible thing.I had initially wanted to go into the research labs to ensure I'd acquire the skill or at least succeed once at injecting buffer saline into the lateral tail vein of the mice as required in the research project.Instead,i ended up with a guilty conscience of having accidentally killed a mice.How did that happen?I have no idea either.Depression set in pretty fast.And no matter how many times i admit to it or try to laugh it off,i still feel something.Sacrificing the mice was suppose to come eventually but it hit pretty hard when it came least expected.Thinking ahead,will i be strong enough to face that if it happened on a human being?I'm learning to control my feelings and detach myself from unnecessary emotions.It all used to be so easy when i was anti social..Have i changed that much in these 4 years?