How do I drop an unfunny cringe friend?

I recently just started six form and I feel like I’ve changed a lot. I feel really mature. I socialise a lot more and I think my humour has changed. My friend is a complete opposite. She is socially inept and immature. Being around her feels like a living hell. Everything she says just makes me want to die. Her humour consists of old TikTok meme I don’t find funny anymore. She’s really annoying as well she’s loud obnoxious and just plain cringe. i’ve been trying to avoid her but I have two lessons sat next to her so I have to deal with her. Sitting next to her is literally a fucking nightmare. I stopped fake laughing at her jokes, but she still doesn’t get the hint. I genuinely lose aura around her it’s not even funny oh my God. Every time I go into class, I just get ready for the mental torture I’m about to endure. I can’t take it anymore. She’s really really clingy too so every time I try to make new friends, always side eyeing me from afar and looks very angry. she follows me everywhere. i’m sick of it. how do I get her to stay away from me without seeming like a bitch? Sidenote, she also smells really bad and I don’t really know how to tell her in the nicest way possible. Please help