Twin Peaks question after finally watching Fire Walk With Me

I finally got around to finishing Twin Peaks season two. I started it when the podcast was beginning Lynch, but sort of stopped watching during the second season. However, his death inspired me to see it through to the end finally.

I don't know if this is something I simply just don't remember from season one of the TV show, but is there anything that indicated>! Bobby killed Mike, (or whomever)? !< There's a good chance I don't remember it being talked about if there were. But Nothing about his character or his demeanor in the entire show indicated to me that>! he just killed someone? !< When it happened in FWWM, I was a little taken aback. Am I forgetting this being explained/explored or is it a new idea in the prequel movie that didn't transition into the show as well?

On a random note. Circa 2002, I was at a friend's house as a kid and we walked into the room his mom was watching a show. The movie/tv show had a woman straddling a man and brushing his teeth so hard that there was blood all in his mouth. (It was very disturbing.) Anyway, I have tried to figure out where this scene came from for years. Google is no help, but another Redditor told me it sounded like a scene from Twin Peaks. Here I am at the end, and that wasn't the case. What was that show? Any ideas?