I dont think its terrible twos... I just think shes entering the trying threes! Dd1 was very similar to this at the same age and it went on till about 3.5! Now at almost 4 shes entering an even more exciting stage called.... let me think... so many names! Oh shes is delightful at the best of times! All we get now is No or you do it... got to lurve the attitude! But getting back to you dd, you havent tainted her for life, unfortunately its just one of those stages. To get her to stop saying for fs sake (which is what mine said too) we had to really cut out our language and swap it for something. Let her know its a naughty word and that you shouldnt use it. When we slipped up we, if she heard, would say that it was a naughty word and would suffer a consequence. Slowly she got it. Youre also doing the right thing to encourage her to use other words to describe her frustration/anger.... Such a trying time. All the best, it does get better for a while......