An ex from hell is an ex-boyfriend or ex-girlfriend that is completely insane. They typically try to contact you constantly, and do NOT want to see you happy in a relationship. They will likely do whatever it takes to ruin your relationships, especially when they realize that your new love is significantly better than them.

In most cases, an ex from hell is a girl. She's usually an ugly bitch who feels threatened by your beautiful, smart new girlfriend.
Guy: Ew. WTF?

Girlfriend: Who texted you?

Guy: That ugly skank Sydney, she wants to have sex with me and has no respect for our relationship.

Girlfriend: Ugh, what an ex from hell.
by The better girl June 30, 2010
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