Is It Possible For A Parent To Take Legal Action Against Me (18f) And My Family?

My younger brother (10M) had friends come over for his birthday party, all the same age. There was an altercation of the sorts between two of the kids. Lets call them Kid A and Kid B. They were playing around and at a point Kid A "chokes" Kid B, or put his hands on his throat for a few seconds, which made kid B scared. Although I wasn't there we had two other kids who were witnesses say that it wasn't with ill intent or anything as they were supposedly playing around. I go to kid B to ask what happened in more detail and thats where he tells me someone hit his leg, and thinking it was Kid A who did it, he hits kid A which resulted in that response. I asked him if he wanted to go home, he told me yes so I called his parents immediately after. Well, they ended up calling me not even a minute after he had got into their car, yelling at me saying what had happened was considered an assault to their child and that they'll figure out what they'll do afterwards (hinting at taking legal action.) The parent then sends me a text message, technically wording what they told me in call. I tried to make the best response I could while scared as shit from this middle aged adult threatening me. In the response we took responsibility for not acting fast enough, respected their wishes to not allowing kid B into our house anymore, told her that the family of kid A is no longer welcomed over, and even explained what had happened. In the end I guess it made them even more pissed as they told me to have a good day. A few extra facts about all of this this is the first time Kid A has came over. Kid B had no injuries or bruises like at all he was just scared and has came over multiple times without problem. The reason in why they only have my phone number added is because of language barriers between my parents. I have asked for the parents to stay at the party when dropping off kid B but they refused. While I really understand the frustration about it as they have a vaild reason for being mad I think calling it an assault is a bit too far. It has really ruined my whole week and im getting worried they will try to take legal action against us since it took place in our house.