Cecilia (Elisabeth Moss) manages to survive Adrian Griffin's scheme in The Invisible Man, but the end of the film probably isn't the end of her story. Cecilia, one of the most sympathetic horror protagonists in recent memory, sure gets put through the wringer in The Invisible Man 2020. She begins the film already a victim of domestic abuse and sexual assault, and after she manages to escape her captivity in Adrian's home, things just get even worse for her.
First she's given a glimmer of hope by the news that Adrian has died by suicide, but she's never truly able to embrace the idea that he's gone, and sure enough, he isn't. A controlling narcissist like Adrian would never end his own life, as he'd rather take out his frustration and rage on Cecilia, who - like many abusers - he sees as his personal property. If Cecilia won't live with Adrian, she won't be allowed to live at all, at least not without being in a living hell.
Of course, she finally does find her way free of Adrian's grip, although not without having to resort to murder. Has committing such an act broken Cecilia? No, at least we don't think so. Instead, we think she's using her newfound freedom to help others in similar situations.
Invisible Man Theory: What Happens To Cecilia After The Ending
While The Invisible Man's ending doesn't spell out that Cecilia is going to get away clean from her invisible killing of Adrian, that's certainly implied, as her cop friend James doesn't seem likely to turn her in for the crime. Yet, she still has the invisibility suit. While she could easily try to go back to living a quiet life after this, Cecilia was made to feel powerless for so long that she'll probably want to do more good. With the suit in tow, Cecilia could become an invisible vigilante, specifically targeting those who escape justice for domestic abuse or sex crimes.
Cecilia could become a sort of avenger, helping other women stuck in a similar situation to the one she was in with Adrian to escape their abusers. Cecilia isn't a fundamentally bad person though, so she'd try not to use lethal means unless she had to. A by the book cop, James certainly wouldn't be inclined to help her, but that doesn't mean he might not be willing to continue looking the other way. Cecilia would be able to fund her heroic endeavors via the millions Adrian left her, which she should still have access to. Adrian's brother threatened to revoke the money, but he didn't get around to it, and later was blamed for everything done to Cecilia. Now that Adrian is dead (again) by another apparent suicide, his will would presumably go back into effect. Cecilia has the means, and the motive, to give human monsters their just desserts, long after The Invisible Man ends.