From the sounds of it, it seems amazing you stayed with him for so long.
I am on my second T. Leaving the first one was not a struggle. I didn't really intend to quit seeing her but I had to cancel our appointment for some reason and on the voicemail I left her, I told her I would call to reschedule, and I never did. She called me back once, I called her again. Phone tag. Just didn't pursue it. We had reached the end of our useful time together and I had come to realize we could go no further with her skill set. I am sure she handled it fine. In retrospect, I wish I had gone for a last session to say good-bye, etc., but I just kind of quit by accident so that didn't happen. Ts are supposed to be professionals and take this stuff in stride. Your T is probably as aware as you are that your therapy hasn't gone well and will not be surprised you are leaving. As Flooded wrote, you don't need to be concerned with how your T will handle this.

As for starting the whole process again, you may not need to. You don't need to go over things with your new T that you've already dealt with in therapy with the T you are leaving. Just go to the new T with where you are and don't repeat material that doesn't need to be. The work I did with my second therapist was completely different from the work with my first.

Good luck.