I have quite a bit of experience with domestic violence as a wife beating alcoholic (jk lol I was a social worker) and my two cents: From what I've seen, the vast majority of these cases are some degree of mutual behavior. I don't care to sit down and speculate re: all LowT's other failed relationships, but at least in this situation and based on his established pattern of behavior, substance abuse (mutual), emotional instability (mutual), what likely happened was pretty much what everyone here predicted.
My personal theory is pretty similar to the "Lowtax smash" post a while back. They likely both got wasted/pillerino'd out, some random thing set one of them off, maybe Lowtax made one of his well-known usual passive-aggressive comments in response to one too many of her wacky zany quirky behaviors, she got set off by it, "what the FUCK is THAT supposed to mean???" Lowtax responds with his usual eye rolling "dumb crazy bitch" under his breath muttering, then flees to his mancave and passes out in a haze like usual, she gets even more pissed because she wants to keep fighting/usual BPD feedback loop, tries to hit/slap Taxman awake so she can get her "satisfaction", LowT doesn't take too kindly to this as he is only 1/3rd of the way conscious and at that level your base lizard brain is still active and overriding any real conscious thought and pops her one. The rest is history.
We all said this was gonna happen, of course. I'm definitely no "believe all women" fag, having seen how this works way too often, but if anything, it's Richardo's own proclivities and behaviors/pattern of behavior that make me believe this. I think some of it was probably exaggerated and from some of Logan's statements it makes me think this is not her first rodeo being slapped around and using emotional manipulation (some of this is a little too on the nose and obvious, like "I fell down the stairs"? Come on) to elicit sympathy/play up her sob story. Also while I do believe she had mixed emotions when she made that "I have committed terrible crimes against the DPRSA" video, she was on some level aware of how forced it looked and felt.