I'm going to bring up that my girlfriend still follows her ex on instagram
Does that bother you?
I hate her for not understanding how bad of a person he was.
You shouldn't be going on her social media accounts like that. Let her life her life like she wants and just put some trust in her. Spying will only lead to more jealously.
A relationship without jealousy is not a real relationship.
I fully disagree with that. There's no need to be jealous in a relationship, it just leads to trouble. You should just let it go.