You can learn to ignore them, remove their comments or posts from your page, or choose not to interact with them, at least for a while. To remove aa post or comment, go to the upper right of the wording and there are 3 dots – hover over them and see the choice to remove. To not see their posts, unfollow them – they still see you as a friend you don’t see their posts. You can search the person and check out their posts occasionally (if you want) – maybe they have stopped the behavior. I had to unfollow a couple people just for posting many times a day because it was taking up too much of my feed – when they settle down, I can follow them again.
To keep them from looking through your personal photos and information, and not let them comment or post (or even see your posts), mark them as an acquaintance, then set up your posts and photos and all as visible to “friends except acquaintances” so no access for them. I had to do this with one who was contacting my friends asking how they knew me and such. Some told me she did this, so I set her up as an acquaintance and restricted her access to my stuff. It’s really a relief because she can’t see my posts and I don’t get the crazy/offensive comments.
So, you can control what, if anything, you see from people on Facebook. It can be a relief to get those posts off your feed. PR