yeah, pretty F'd up :thumbdown Can't blame you for being a bit bitter.
To my own admission, of all the years I have tracked (and raced), I can account for a couple of blunders I've had - intention to late brake to pass a pack a slower riders, only to have miss shift and blew the corner. Fortunately, the pack adjusted to my mistake, and continued their way. After the session over, I had apologized to the riders.
The other, again, involved a slower rider - missed judged their intention. Well into a session, on a lap of following a few corners, thought the rider was going to take a wider line, and I made a pass to the inside, only to have the rider take a tighter line, while I was in the midst of making the pass, and had bumped bars. We both made it through, and am pretty sure the rider was a bit shook up, I put up a hand of an apology, as well as apologized after the session was over.
Another, where I was coming up on a slower rider into the Bus-stop at Stockton, while making the first turn into the chicane transition, the rider decided to come to or to a near stop to allow me to pass. Issue was, I was not prepared, and had set myself to follow the rider thru the chicane (as I typically do with other riders), with intentions of passing once on the straight. Any regard, I was in deep, reacted too late, applied a hand full of front brake to low slide, which carried me into the riders back wheel. I went down, he stayed up right. In the end, I got the worst of it - tore my MCL and a meniscus tear in my left knee.
I chalk each of these episodes as a lesson(s) learned, and approach slow riders a bit differently these days - a bit more reserved and patient.