AITA for calling my little brother a selfish a__hole for making my life miserable?

A 21-year-old woman has carried deep resentment toward her 13-year-old brother for most of his life. From the moment he could walk, she says he tormented her—invading her room, stealing and breaking her things—while their parents dismissed it as normal kid behavior. She felt neglected, punished for minor things while his actions went unchecked.

As teens, the dynamic turned physical: she admits slapping him out of frustration when younger, and he later hit back harder once he grew stronger. On his birthday, after she sacrificed to buy him a Nintendo Switch, his cruel rejection pushed her over the edge—she called him a selfish asshole in front of everyone and stormed out.

‘AITA for calling my little brother a selfish a__hole for making my life miserable?’

The trouble started early in his life, when he was just learning to explore the world:

Favoritism became obvious during his activities:

The breaking point came at his birthday party:

Sibling rivalry intensified by clear parental favoritism can leave lasting scars on everyone involved. When one child feels consistently overlooked, resentment builds quietly over years. Dismissing the older child’s complaints while excusing the younger’s behavior sends a message that their feelings don’t matter equally.

Physical responses—from either side—rarely resolve underlying pain and often escalate the cycle. The older sibling’s initial slaps stemmed from unaddressed frustration; the younger’s later aggression mirrored what he learned about power in conflict. Family therapist Dr. John Gottman has emphasized that “unresolved childhood resentments often manifest in adulthood as emotional cutoffs or explosive confrontations.”

The birthday outburst, while harsh, came from accumulated hurt rather than isolated cruelty. Rejecting a thoughtful gift with insults would sting anyone, especially after personal sacrifice. Parents demanding only one apology ignores the broader pattern.

Healing starts with recognizing the parents’ role in creating division. Therapy can help process neglect and resentment without directing it at the younger sibling, who was also shaped by the same dysfunctional dynamic.

Here’s the input from the Reddit crowd:

Online reactions were mixed but leaned heavily toward calling the sister the asshole for physical abuse and long-held resentment, while blaming parents most:

This family is caught in a painful cycle of favoritism, neglect, and retaliatory hurt that no one seems to have broken yet. The parents’ uneven treatment planted the seeds; physical actions from both siblings watered them.

Years of built-up pain don’t justify cruelty, but they do explain it. Have you seen dynamics like this in families—where one child’s frustration gets redirected at the “favored” sibling instead of the parents? Would therapy and distance help rewrite the story, or is cutting ties the only way forward when trust feels permanently broken?