is it considered slander if a person u told something very private about tells others without your knowledge?

Answer 1

Nope, it's called "gossip"
If they post it in the newspaper or go on the radio, different story,
even then I believe they must publish names also. However, I personally we be quite upset and would need a serious talk with this person.

Answer 2

Well, for it to be slander, it has to be untrue, so no.