How do I block someone on facebook that has already blocked me on a mac?

[Magnum Garcia]

Hi guys; I'm not very good with facebook, but I really need to know how to do this; there was this toxic girl stalking my profile, and I told her to quit stalking me, so she blocked me. Oh, I should probably mention that I did the initialchatfriendslist thing from viewing the page source in order to discover that she was stalking me. Anyway, her number keeps coming up on my initialchatfrienslist, so I know she's still able to view my profile, but I can no longer view her page, and when I type her name in to block her, then it will only give me the pages of others using the same name. How do I block this toxic girl? Thank you very much for your help.