Calling shias kaafir

As salaamu alaikum

A few months ago, someone was telling me about a shia friend they had who did not seem outwardly deviant who’s house he ate at. I genuinly believed that all shias were deviant and at that time I was not aware that there are some shias that can still be classified as muslims as I only read this yesterday on an askimam answer. It bothered me that he ate at a shias house and while debating with him, using what I had heard about shias (such as their different Quraan, what they do on muharram and their reverence to Ali RA and his son) I said something about them doing acts of shirk and kufr and that they are kaafir. I cannot remember exactly what I had said about the kufr and shirk but I definitely said shias are kaafir a few times (maybe 2 or 3). I cannot remember if I was thinking about his friend at that time when I generalized but there is a possibility since this was the start of the conversation although I have never met his friend as this was a college friend so not one of his close friends or someone he associates with still. A third person present there told me I should not call muslims kaafir. At that time I was not aware of the hadith that says something to the effect that if u call a muslim kaafir u become one. The thing is, I genuinly believed that all shias would not be muslim right until a few days ago so even though the person told me about not calling muslims kaafir, I still felt afterwards that shias would not be muslim until I read the post yesterday. I am now worried about if I have become kaafir by making such a statement as some shias might still be muslim.
1. Did I become kaafir by saying shias are kaafir?
2. Is my nikaah valid?
3. If someone says shias are generally kaafir, would this make them kaafir?