AITAH for telling my ex boyfriend's daughter, "It's not my problem." ?

I (38f) dated John (40m) for about 6 months (we had known each other for a year before we started dating). We broke up 3 months ago.

The reason for the breakup was because of his daughter, Tia (16f). From the very beginning she was hostile towards me. Rude comments. Putting me, my cooking, etc down. Constantly referring to me as "that bitch". She said I was the reason her parents broke up. (False. They broke up 10 years ago, 9 years before I met John).

I have a stepmom who went out of her way to try and push her way into my life. So I actively did everything I could to be the exact opposite. I tried to give her space. I tried talking to her, asking her what I could do to at least make things between us civil. Her answer: I could voluntarily leave this world.

John was no help. He'd threaten to ground her, take her things away, but they were empty threats and Tia would just continue her tirade against me. Her mother, Chloe, (who honestly is awesome) even tried to talk to her and figure out what her problem was. Tia couldn't come up with 1 reason why she didn't like me, she "just didn't."

It all came to a head one night while they were at my house. We had ordered food and I went to go pick it up. When I got back I found John in my dining room, sweeping up the remains of my grandmother's antique pitcher. My grandmother meant the world to me so seeing the pitcher destroyed broke my heart.

I demanded to know what happened and Tia gave me a smirk and said, "Oops. It was an accident." I asked her how it was "an accident" and she just shrugged and said something like, "I think I bumped the table and it just fell off." There's no way that can happen. My dining table is heavy. You would have to slam yourself into it to even shake that pitcher.

I told them to leave and spent the rest of the night crying. The next day I called John and told him I couldn't do this anymore. He tried to talk me out of it, but my mind was made up.

Fast forward to 2 days ago. I leave work and there's Tia. She started going on about John's new girlfriend, Jane. How Jane is a monster. Evidentially Tia tried her old tricks on Jane, but Jane gives it right back to her. Tia calls her names, Jane calls her names back. Tia insults Jane, Jane insults her back. The worst was that Tia "accidentally" broke something of Jane's and in retaliation Jane took Tia's phone and smashed it.

I asked her if she had told her mom. She had and Chloe decided that Tia wasn't to go over to John's anymore. I told her something like, "It sounds like everything's settled then." Tia started crying, asking if that was it? I just looked at her and said, "Yep. Your mom handled it. It's not my problem." And I left.

I was talking to my sister about this last night and she called me an AH. She said that obviously Tia is hurting and needed me. She came to me for a reason and the least I could have done was be a shoulder for her to cry on. I just don't feel anything. I think I'm just numb to Tia now.

So AITAH?