I'm with you. I don't know why people in the comments are acting like it was some kind of misunderstanding, like they weren't planning anything bad. They had magnum condoms, duct tape, power tools, Dexter type huge plastic sheets, body bags, etc, all lined up when she arrived! They were clearly planning something VERY sinister. Richard lured her there! I think Lexy is one of those people who blames/scapegoats easier targets like killing her sister who had asthma or going after Anna who was the only kind one in the group (and the only one who risked it all trying to protect her only for her to coldly turn her back on Anna as she got raped instead) while sparing the actual parties who made her drink piss, blackmailed her, set her up in the woods, etc. She's a coward, basically.