Taylor Swift's "Bad Blood" video: Sorry, I missed something

Hello, Ms. Swift.
Thank you for joining me in my little corner of cyberspace. Please make yourself comfortable. I certainly won't blame you if you don't stay long.
I had to look up the lyrics to the song to make sense of the video. What I seemed to hear during the first watch-through was a repetitive complaint of betrayal, directed at either the dark-haired woman who kicked your character (may I refer to her as "Jane", for brevity's sake?) out of the window at the beginning the video, or Mr. X, the featured rap-artist (presumably portraying Jane's boyfriend). With the lyrics, I was able to understand that Jane was explaining that the betrayal had left her in profound pain, and that forgiving the betrayer was not going to be possible.

To be fair, I'm turning 45 on 30 Nov 2015, so my ears are probably not longer sharp enough to pick up certain details from the audio track. I've also never had a falling-out with anyone so profound that I felt the need to go through the kind of "training montage" that Jane endured during the main "body" of the video, so I freely admit a lack of comprehension of that aspect of the story.

If you're still with me, I do have a few questions.
First, I understand that the "elite secret sisterhood" motif was meant to symbolize that the betraying woman was once Jane's most trusted friend. Given the resources that Jane clearly can draw upon (those experts training her in all manner of mayhem won't come cheap, either in money or favors), is there any particular reason why a high-level operative such as her wouldn't bother to investigate why the betrayal took place at all?
Second, who are the people smoking cigars while sitting around the table monitoring Jane? Are they her bosses or the ones who inspired the betrayal?
Third, the lucite car mock-up you shared with Mr. X was admittedly a very cool visual, but what was its purpose in the context of the video? (And does it seem like it designed with a right-hand drive?)
Fourth, I understand that the song isn't meant to be "interactive", in the sense that Jane isn't interested in hearing the betrayer's response (given that the lyrics clearly state that the betrayer doesn't care about Jane's feelings), so why is Jane even bothering trying to express her feelings at all?
Finally, the end fight scene is choreographed to set up the audience-expectations for a climactic battle, where all of Jane's new skills are put to the test. So why did the video end with what looks like the beginning of a Three Stooges slap-fest? Is it meant to imply that both Jane and the betrayer are so emotionally distraught that they regress to junior-high-level fighting instincts?

In the end, I found the video to be a visual treat, with Jane building up her rage at the betrayal and channeling it into making herself into an even more dangerous "combat machine", but I felt disappointed by the ending.

Thanks for visiting, and I wish you and yours the very best.