How to know if someone has access to my iCloud account?

Hi, this is my first time asking a question here, so please bare with me because I know very little about technology and the security issues with it. I have found myself in a bit of a predicament. About a year ago, I gave someone the email and password to my minecraft account. I have not accessed the account since then. Now, I cannot access it at all (I barely knew the person I gave it to…yes I know that was extremely dumb. I realized that the same email and password was my Apple ID information at the time. I have since changed my password, but it’s the same email. I think that person may have sold my Minecraft account (which I did not know was a thing until recently). I looked up a bunch of stuff about spyware and what someone can do with you Apple ID information…and it’s very concerning. How do I know if someone has been looking at my account? Could some random hacker/bad guy been looking at my account this whole time? I’m really not sure what to do. I don’t want to spend money on a spyware scan if it’s useless. I checked to see if any other devices were attached to my Apple ID and it said there weren’t any, but I don’t think it would show if it was a hacker that had access or something. Like I said, I don’t know anything about this stuff. I just want to make sure I’m safe and my privacy has not been breached. I saw that when I backup my phone they could still see even the new information that was backed to my icloud if they still have access (by they I mean a hacker or someone like that). I feel so dumb for getting myself in this situation in the first place, but I would just like some help.

[Re-Titled by Moderator]