Ok so they can see the posts but I can't. How can I block someone from seeing MY posts as well?
You can't, and here's why:
Think about it this way: If you put me on your ignore list and SUPPOSE that I can't read your posts that way. Well, **I can simply
1) log on with my other ID and read your posts 2) if you block ALL of my IDs, I can simply log out and read your posts as "unregistered" member.**
So even if there was an option where blocking someone means they can't read your posts, they will still have a way to read them.