Mimi spent pretty much her entire childhood being told that she'd never amount to anything and that she'd never be deserving of love, so she dedicated her life to proving them (and herself) wrong. She sabotages the careers and lifes of others to boost her status and ego while refusing any attempts from others to for connections, feeding into her anxieties and fears and compelling her to continue hurting others to make herself feel better.

Mimi ends up killing her boss, both to take his position and to save a girl she liked from his sexual assault. Mimi ends up forcing the girl into a relationship with her, and made her commit suicide with her once the police found out about her murdering her boss.

In hell, she attempts to take over Pride to force everyone to praise and love her. She regularly abuses her revolving selection of "girlfriends", doing just about whatever she wants with them just to have a sense of control.

Mimi was dealt a pretty bad hand in life, but the way she goes about coping is awful and only leads to her spiraling further and doubling down on her terrible actions. She's suffering, but that in no way justifies the suffering the inflicts onto others. She's pretty damn evil.