I got friendzoned recently (in a kinda cynical fashion too) and I almost felt my T fucking plummeting just being near her. Text her the very evening that I don't want none of that shit.
She's a girl from work and our desks are literally within 2m from each other. I am completely ignoring her and don't even reply when she @'s me in our work chat. Sometimes I fell bad, but then I remember how I felt after all that shit she said to me. Sometimes it feels like she wants to make up for that shit, but I'll just keep ignoring her, I don't want to feel like a complete fucking beta since it always starts to leak into other fields of my everyday life ruining communication with other people, hobbies, etc.
tl,dr: Fuck friends. We're not 15 or in some Disney movie. Say you don't want to spread your attention to constantly growing pool of people, but better dedicate it to a single person who actually cares. If that ain't you, bitch, well too bad, bye, we're no friends.