Along way, you may not think you can express your feelings well in words bt you do convey the feeling very well anyway. It sounds like you still have a lot of expectations about how your wife (girlfriend) should be. My guess is that she doesn't want to cooperate in those expectiations whatever they might be. Can you try just not expecting anything from her? About saying "Hmmm, how will this call be? Oh, so that's what's happening. Funny, she went off the stick there. Hmmm."
It is very hard to do. It took me years before I realized my father in law COULD NOT live up to my expectations of how a man his age should behave. When I finally did, I was able to distance myself enough to stop trying to change him and to stop responding to his jibes. It made life much easier.
I suspect that once you feel that you can regain control over some part of yourlife, even a small one, your self confidence will start to recover. It's usually not a catastrophe to fail. It might be worth trying for something you have never done before. If you are honest and you still get picked, then the boss thinks you've got it. rely on that. Good luck, We're pulling for you!