AITAH for refusing to help my sister "move on" from her ex?

For context, I (19F) have always been the person my older sister (whom we will call Gwen) confides in most regarding her relationship. Back in 2019, my sister finally got her first official boyfriend, and I was the reason why. It was always on and off throughout their relationship; they always argued, and one always had something to complain about. It was honestly really toxic, despite this, I was the person who always helped my sister woo her boyfriend back as well as give her advice on what to say. This kept going on for years, and I never once complained about helping her. I was basically a couples counselor to her, even though she doesn't even listen to half of what I tell her.

Fast forward to 2023, my sister and her boyfriend break up what seems to be for good as the guy literally does not show any care or concern for my sister anymore. All my sister has done throughout this time is complain and rant at how mad she is with her now ex, saying he's so dumb, and he never changes.

Back in December, my sister again asked for help to try to woo the guy back, which I agreed to do even if I was against it because I wanted to make her happy. Unsurprisingly, it didn't work as he replied that he was just done with my sister. Now, she just learned new information that her ex is now seeing someone new, and based on his recent Instagram stories, he really likes this new girl and has been pampering her with gifts like a diamond ring and a dinner date. My sister once again is asking for my help, begging me to congratulate him and see his reaction so that maybe she can find peace. However, unlike the other times, I refused, telling her that if she wanted peace and closure, she should be the one to message him so she could get answers to questions she had instead. She kept trying to force me to just do this for her and be a good sister, but I put my foot down as I knew for a fact this wouldn't help her move on. I told her that whenever she gets news or information from other people, it only makes her obsess over him more. Case in point, when I get her the information or when she learned about the ex's new girl from another person. Thus, it would be better for her to talk to him herself. After this, she got really upset at me and told me never to speak to her again and that I should stop talking because she did not care what I had to say. Now, she's blocked me on every platform, and I feel both angry and a bit regretful. I love and worry for my sister, and I just don't want her to keep looking like an idiot over a guy who clearly does not care for her.

So, AITAH?

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extra info: (the only other time I refused to help her when she asked me to ask her ex who was this new girl because I knew she would just obsess over it)