Ex was to immature and not good for me but I still want to get back with her

I recently broke up with my ex because of an ultimatum I did because I couldn’t take it anymore. At first I thought I did the worst thing ever and really wanted to get back with her. But as the time goes by im starting to realize its what we needed the whole time but aven if I know I can’t accept it. And today I just realizes that she never broke up with me because she always try to run away from problems because she prefer to suffer instead of making the effort to find a solution. So now I don’t know what to do because I saw her repost and damn they were mean like im so happy im alone now it wasn’t the love of my life anyway, things that say she want to flirt with his friend which I suppose its her ex since they are in the same friend group. I just can’t take it anymore I don’t know how to act what to do I put everything in this relationship while she did nothing to make it better. I want to see her again but at the same time I really don’t.