"I'll keep you, my dirty little secret"

I have been in a situation where I didn't want multiple people to a secret of mine. I acted very differently. In fact, I avoided them as much as possible. My avoiding them didn't help the situation at all because it made them extremely suspicious of me.
Eventually, they discovered my secret and well, it wasn't a very pleasant experience. Once they found out, it all blew up in my face and it wasn't very pretty. Trust me.
Normally I can keep secrets extremely well. Unfortunately, I have to be the absolute worst liar imaginable. If you start asking me questions about something, you will no doubt find out within a few minutes what I had been keeping from you.... I shouldn't have told you that.