Wondering what others would have done in this situation, sorry for the novel.

DD (22 months) and I were at the playground this morning. When we got there as we were walking in a mother warned us to be careful of a girl being a bully - didn't think much of it. DD was running around playing and I saw a girl push her down the slide. I went over and nicely said "please don't push" to the girl, I'm guessing she was 4ish. A few minutes later DD was playing with these large drum things and the same girl came over and shoved her to the side, knocking DD down. The girl runs away when I try to say something to her. 10 minutes later DD was on the main structure and this girl came over and pushed her off the structure at a ladder opening - four feet of the ground! I run over to DD and the girl ran away. This whole time her mother is sitting on a bench on her phone.

As soon as DD was calm and I felt she was okay, I approached the girl's mother to ask if she saw what was happening. She said yes but that's how kids learn. I was pissed at this point and kind of went off on her but could tell she didn't care. She had no intention of getting off the bench or talking to her daughter. At that point I gave up and DD and I left.

I called DH when we left the playground because I was pissed. I told him what I did to handle it and he disagrees with my actions. Wondering what someone else would have done?