Can someone do something bad to you and justify it by saying you deserved it because you are a loser?

No one has the right to say that to you. Usually when someone calls another person names it's because they are usually the ones that are mentally deficient and a loser! Don't take this from ANYONE! We all make mistakes and we all have to learn from them including the person calling you names. Tell him/her to take a hike!

Answer

No someone should not do something bad to you and justity it by blaming it on you that's victimizing you a second time. What ever this person did let someone who can help you know so it doesnt happen again. Im sorry that someone did something bad to you, people can be cruel and those people need help.