AITAH for telling my ex’s new girlfriend about him trying to add me again?

Hi! Let me start with this was a relationship that only lasted a few months and we split up because of bad arguments. Lemme start from the beginning so it all makes sense. Let’s call my ex Brandon, his girlfriend Alyssa, and Alyssa’s sister aka my friend Harley (not their real names)

I (17 F) and my ex (17 M) broke up back in august. We would constantly argue and I got sick of it and we both went our separate ways. After about 2 weeks we got back together for a few days before I broke it off again and cut all contact. The only contact I’ve had since then is to his step mom because she has always been really sweet and we had a good friendship. BUT THATS BESIDES THE POINT.

A few days back me and his step mom were texting back-and-forth and she told me that my ex and her were talking and he said that he had missed me and that he thought that me and him would never get back together, and I told her the truth telling her that I did not wanna get back with him.

(because of how much he put me through because I could not talk to my friends I couldn’t hang out with who I wanted to I couldn’t go to the gym I couldn’t do anything that I love to do because I was being so held back because he would get jealous or upset.)

Well sometime last night while I was asleep, he added me on Facebook. Now mind you, I am friends with Harley (his new girlfriend’s sister) and have been for a while since we used to go to youth group together before I left. And I know his current girlfriend (but not like a best friends way.)

When I woke up and saw he added me I took a bunch of screenshots and I called Harley and asked her to text Alyssa and tell her what’s going on because I didn’t want him to lie or it cause drama between me and Alyssa cause I have nothing against her. She did and Alyssa was glad I even reached out and told her.

I don’t wanna ruin their relationship but he has no reason to reach out to me when 1. he has a girlfriend, and 2 he caused me so many mental health problems, and 3 because I told him specifically to never contact me again and never contact my family or friends either.

AITAH for telling her about him adding me or should I have stayed silent and just deleted the request?