My neighbors and I have kids around 8-9 years old, and we live right next door. The children were in…

My neighbors and I have kids around 8-9 years old, and we live right next door. The children were in the same group in kindergarten but weren't close friends. When they were still in kindergarten, her son hit his head hard against a wall and cut it open, bleeding badly. He was always a bit unstable, and his mom struggled to manage him. She even said things like, 'I wish a car would hit you.' That incident was the last straw for me, and I definitely told them they wouldn't be interacting. We stopped greeting each other. Then the kids started school, and he wouldn't even say hello to me, even though my son always greeted him. They ended up in different classes at school. Yes, when we'd occasionally meet at the playgrounds, he'd circle around me like I was crazy, just not saying hello. Later, we started greeting each other again, and sometimes even exchanged a few words about school. Now, there's construction at the school, so her son attends the same school as mine, though in different classes. The boys have started gravitating towards each other, chatting, and growing up. I hardly see her anymore. They started knocking on each other's doors and chatting in the common hallway. I casually suggested they come over to our place, and then my son could go to theirs. He has his own room, unlike us; we had a two-bedroom apartment, so it would have been fine, but it's inconvenient in a one-bedroom. Nevertheless, they occasionally visit each other. She's particularly odd. In front of me, she'd badmouth everyone she'd been with and call children names like 'fatty' or 'weirdo.' Just so you understand what she's like – a real gossip. That's how I knew from the start. Yesterday, her son knocked on our door again, and they went to their place to play. Everything was fine. Then my son came home and said her son told him his mom doesn't allow him to hang out with mine. It felt so unpleasant. The kids have grown up, I'd forgotten that incident, and yet she says things like this. Who knows what she's telling him, and he, being young, told me. I'm thinking: the kids are friends, they like each other, he doesn't bother mine anymore, everything seems fine, but she says this to her son. Should I just let it go or write to her? But her son tells her he'll still come over because he wants to hang out with mine. 😃 I don't want to put him in a difficult position either. So that's the situation. I have a quiet and calm child, and I've never interacted with her or said anything negative about her, just for your information.