Help!!

Followers, i need your help please.

I found out someone is reading my blog, and at first i didn't know who it was. Now i do, and would prefer that they didn't read it.
(would go into who they are, but with them reading and all, don't really want to, lets just say, they aren't in my life, so i don't want them to know about my life).

Anyway, I'm not all up on this computer stuff, and i checked the 'help' (pfft) section and i can't figure it out.

How can i stop them from reading my blog?
Is there someway to delete them from reading even if they aren't following?
Is there someway to stop them from reading while still keeping this a public blog and not having to 'approve' the people who read it? Which would get super annoying?

Either way, i really would like it if they stopped right now and never had me have to write this post, but i don't know if this will happen.

Please followers, i would really like some help on this if you don't mind.
Its really off putting, knowing that this person is reading.