What is the percentage chance of my child being born with cf when i am a carrier and my husband is not a carrier? i know close to zero, but how close to zero?

Zero, unless there is a new random mutation only at that spot (rarer than rare). The kid will either be a carrier or not & you cannot change this if you have the baby.

Mendelian genetics would assert that half your children will not inherit the CF gene. Since your husband does not have a CF gene to pass on, at worst, half the children would be carriers and half noncarriers. There is a one in a million chance that you will have a new point mutation in your husband. Informally, you may let it be known that you have a one in four million chance.