My T gets frustrated with me ALL the time, ALL the time. I also get frustrated or angry with her. Sometimes I am scared that she'll begin to hate me but she says that the negative feelings are transient. She chooses to see the entire me rather than the behavior that's upsetting her. I appreciate that! She must often strive to see the good in me.
Don't worry about your T rejecting you! They know what to expect and how to respond and/or cope.
Oh once my T told me that I have said some things that would normally turn her off but for some reason she still feels very connected to me. That was several months ago. She has since told me she loves me. It'll work out, Sky! If anything, your T will be very happy that you were brave to share difficult things with her.