I knew what you were thinking.
I knew who you were talking to.
I knew what you wrote, what web sites you visit, how long you spent on each page and what caught your attention on each page.
I knew who all your friends and family were.
I knew what you liked and disliked.
I knew what you did last week, last month and last year at 22:30.
I knew what you watch.
I knew how much money you make, and how much you spend.
I knew all your investments.
I knew your diary/calendar.
I knew when you were home.
I knew what you bought and when you switched it on/used it.
I knew where you lived and where you went.
I knew what medication you took or were thinking of taking.
I knew when you were trying to hide your tracks.
I could legally break in to your personal information without a court order, and without your knowledge.
I could manipulate what you think based on the information above.

I decided I didn't like you?