I don’t think you are control freak. I am, too, very strict with my students. The same thing that is “killing” you “kills” me too, but since I couldn’t win – I decided to pick my battles with students.
I was never satisfied with my students’ playing, for it was always something missing in their interpretation. That used to drive me crazy, so my job became very stressful rather than pleasant. Over the years I realized that not everybody was born to be a musician, so I should not expect perfection. I always try to pull out maximum from each student, but sometimes they just don’t care or, as you said: “they don’t get it”. That’s why I decided to ask for most essential elements, such as perfect timing and reading notes. Once when they feel OK with these two things, I slowly move on to perfect phrasing, dynamics and other elements they need to know in order to enjoy music.
I have students who quit with excuse that it was too much what I was asking from them, but to be honest, I never regret when I lose student with no motivation. However, I have more room for somebody who might be better.
I don’t worry too much about motivating students, because those who are not motivated honestly – it is more likely they will never be. Motivated students are always happy with any kind of composition I assign and they never resist to practice the way which is sometimes kind of boring, but very useful (such as having beginners tell the notes out loud as they are playing along).
I felt the same way as you do now, so I had to readjust my teaching “style” in order to save my nerves. It worked for me.