I’m not sure if you were aware of this, but she’s playing a character in the song and video.  She wrote “Blank Space” as if she was how the media portrays her: a flighty floozy who falls in love quickly, gets controlling and jealous, then ends the relationship suddenly with a petty revenge song. 

She’s well aware of this caricature and makes fun of it in the song, acting like that person… to an extreme!  Living the high life with indulgences, becoming manipulative, then seeking psychotic revenge.  If you watch the full video you can see her lose her mind, and she doesn’t shy away from that, doesn’t disguise it:

She KNOWS she’s reacting inappropriately, and that’s the point!  While she doesn’t give herself a name like Slim Shady to create an alter ego to separate herself, she might as well.

If I hadn’t known ahead of time that she was using this song and video to mock the public’s opinion of her, yeah, I’d be upset as well.  Abuse is never okay.  But she’s actively acting insane to show that that’s the kind of person that (verbally, mentally, physically) abuses another.

I agree that it is problematic that more people are going to laugh about this than videos like Eminem’s “Love the Way You Lie”, but the two songs are portrayed and handled differently.