I was out biking today and thinking some more about this Leah and I realized that I may have come across as argumentative which wasn't my intention. I think what I'm trying to get at is that I believe you should have a pretty secure attachment to your therapist. Kind of like a child with their parent (ideally--I realize that many of us did not have this). Can you imagine your child disagreeing with you or questioning you and saying to her/him "well sweetie, if you don't trust my judgment maybe I just won't be your mama anymore!"
Of course we get mad at our kids and say stuff we shouldn't. But then it's our job to fix it. Our kids shouldn't think "if I make her mad she'll abandon me." A therapist has some amazing advantages compared to a parent: special training and education, dealing with one person at a time for a very limited time, generally working during peak productive hours etc... It shouldn't be so hard to keep from losing it with your client.