I feel so terrible, but I matched with my best friend’s old crush on Tinder last week. Nothing even happened, but she found out and now our whole group is sitting in my living room completely ignoring me like I don't exist. In my own house. Am I really that horrible? I feel sick and don't know if I should just hide in my bedroom.

You are not horrible, and you do not have to hide in your own bedroom. Swiping on someone your friend used to like isn't a crime, but orchestrating a silent ambush in your family’s house is manipulative and petty. Your friend feels territorial and insecure, so instead of admitting she’s embarrassed or jealous, she’s recruiting an audience to punish you. It feels devastating right now because they are actively freezing you out, but this dynamic only works if you shrink. Don't apologize to the group, and don't sit there taking the cold shoulder. Walk downstairs and reclaim your space by ending the hangout. A calm, direct: "Hey guys, I need to wrap things up for tonight, so let's call it" takes away her stage. Once everyone leaves, you can message her one-on-one: "If you're upset about Tinder, we can talk, but freezing me out in my own home isn't okay." A good friend tells you when their pride is stung; they don't stage a silent trial in your living room.