My twin sister and I have always had an extremely close bond. She recently gave birth to her first child, and I’m overjoyed to become an aunt. Last week, she asked if I could watch her baby while she went to a special event, and I eagerly agreed. However, just days before the event, my boyfriend revealed a secret about my sister, which turned my world upside down.

My sister’s decision, which had a direct impact on both her and my life, had been kept hidden for years. What hurt even more was learning that, back then, when my now-boyfriend was her closest friend, she confided in him rather than me. I was deeply hurt to learn that my sister trusted him with something so important while keeping me in the dark.

After high school, both of us applied to the same university. I was rejected, whereas she was accepted. For years, I attributed it to bad luck on my part. But, according to my boyfriend, my sister was initially on the waitlist. She had written an emotional letter to the admissions office, which ultimately led to her admission. What’s the twist?

She used a personal story I shared with her about a difficult time in my life as the centerpiece of her letter, without informing me! When I confronted her about it, she hesitated before finally admitting the truth. She defended her actions, claiming she was desperate at the time and assumed I’d understand because she thought it was best for her future. She insisted that her success at university was the result of her own hard work and that it shouldn’t matter anymore. For me, it was more than just the letter. It felt like a betrayal of trust when she used something deeply personal to her benefit without my consent.

I declined to babysit on the scheduled date. I stated that I needed time to internalize my knowledge and was not emotionally prepared to care for her child. She didn’t take it well. She accused me of punishing her and her child for an incident that happened years ago, calling me immature for failing to move on.

I can’t continue to act as if nothing has happened when my faith in her has been severely shaken. Our parents disagree: my mother believes I have every right to be hurt, whereas my father thinks I am being petty. I’m currently unable to communicate with my twin or partner. I’m left wondering whether I overreacted.