Snape was bullied a lot during his time at Hogwarts by James Potter and his friends and no one but Lily tried to stop them so Snape had a pretty rough life there, being called names all the time, being abused with magic, all sorts of things. But he never stopped having a rough life, when Harry Potter came to Hogwarts he got sorted into Gryffindor which would be hard for Snape because as a child he was bullied by Gryffindors. Snape was an inside spy for Dumbledore which would be very stressful as he would have to make sure Lord Voldemort didn't find out that Snape was spying on him and be convinced of his loyalty, he also had to kill one of the men he most respected and pretend to turn on Hogwarts and Harry, Harry the one thing he had left of Lily. His death was also hard as he spent all that time getting close to Lord Voldemort just to have him turn around and kill him for mastery of a wand Snape wasn't the master of, his school was also under attack and he knew not of whether Harry would succeed in killing Lord Voldemort or not, he had to make sure that Harry had an explanation for what happened and just hope that Harry would forgive him and also ensure that Harry got the knowledge he needed to defeat Lord Voldemort.