I started a new job and a manager began to speak in a very annoying way. I can’t have completely misunderstood what they said. I’m considering going to HR, but I’m scared it might get me fired. What course of action should I take?
I don’t think you should postpone going to HR. I mean, if you cover up such disturbing conversations, they’ll only become bolder in the future. A friend of mine had this happen at work; he was hesitant at first, but when he spoke up, the guy got reprimanded. If you get fired, that in itself is grounds for a lawsuit.
Have you opened up to someone else before going to HR? I mean, to a trusted teammate or someone like that. It’s easier to approach HR when you’re in an environment where you don’t feel alone. I once talked to a friend about something similar before; they encouraged me.
But I want to ask you something, don’t take it the wrong way, what did you say that made them start talking like this? Maybe you misinterpreted what they said? Because sometimes, in such matters, intention is very important. Perhaps there was a misunderstanding from the start? 
I swear the HR in the company I work for doesn’t seem to handle these matters very well, but I remember the procedure was like this: first, you prepare a written complaint letter, then you have a face-to-face meeting. But keep records of everything so you can show it as evidence if necessary.
I talked to someone as you said; I have a trustworthy friend. He also says to go to HR, but to be honest, I still have concerns that the manager might treat me differently, like they might blame me.
If you’re going to HR, try to speak directly and clearly about the disturbing sentences. I mean, something like this: ‘On this day, they said this, and it happened exactly like this.’ If you speak abstractly, it will be hard for them to take it seriously.
Let me add something as well, be sure to take written notes of what you said. What day, at what time, write it down word for word. Because if things get serious, you can show this as evidence.
When you become someone significant, it’s easy to feel overwhelmed, and I’ve come to understand this very clearly from your writings. But if you continue to doubt, it will be a burden on yourself every day. Constantly recalling those sentences can be tiring.