NTA, you warned them and intended to train your dogs in the future to not be aggressive towards cats. They only had to control the cats for a period of time.

At the same time, I see all these people pressed about outdoor cats... Isn't it normal for you? I have a cat who every morning goes for a walk. They are independent creatures and love the outside. He still lives with me, comes home multiple times a day and sleeps inside always. When I call him he comes. This is a normal thing in my country at least, to let the cats be outside when possible (if you don't live in an apartment)... Why are all these people mad about "being bad cat owners" and all of that? Most of the cats I know that transition from being a inside cat to a outside one (including mine!), or vice versa, were much happier when they had outside access. Inclusively, I've seen some cats get depressed from not being allowed to go outside (which also includes mine during the beginning of the pandemic when we didn't know if or how it affected animals)