Had a falling out with my sister last September and I have no desire to talk to her. After months my niece reaches out and I ignore her. Is it okay?

My niece is 12 and lives part time with my sister out of state and part time with her dad here in our city. The falling out was in September of 2021 and not once did my niece bother telling her dad to bring her to come visit or anything. I haven’t heard a word from her since September. Yesterday my sister came to visit my mom and my niece came but I was in my room working and didn’t come out. While they were outside my niece came in and tried knocking on my door crying asking me to open the door but I ignored it. I understand it’s not her fault what happened with my sister and I but in a way I no longer want any type of connection with my sister. As for my niece, she had since September to ask her dad to bring her to visit and she didn’t do it (she’s asked him in the past and he listens) so yesterday when she randomly came knocking I felt like it was too late in a way. My other sister says it’s for the best to keep my distance because last year I hit an all time low due to that drama and quite honestly don’t wish to open that chapter anymore.
Had a falling out with my sister last September and I have no desire to talk to her. After months my niece reaches out and I ignore her. Is it okay?
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