<human>: Condense the text into a few key points

I want to start by saying I have never dated anyone. I met this girl who was my age around a year and a half ago right after she broke up with her boyfriend. I've been with her ever since and we've grown into best friends. I developed feelings for her over time but they aren't mutual as she says. It didn't bother me much until now because she has been independent and getting over her last relationship. However, recently she's been telling me about this guy she met who was a complete asshole to her and how she only wanted to be friends but his actions put her off. Until a few days ago she confessed how she suddenly met up with him and they made out and things are moving. She hasn't mentioned dating him but I don't get how she suddenly went from hating to that but whatever. The issue for me is how I suddenly felt when she told me. I've been feeling crushed ever since and every time I think about it or she tells me they're hanging out or what they do it destroys me from the inside. We don't live near each other so most of our days used to be spent video calling and I know she owes me nothing, because how would we even be together. I read a few threads which say I should just tell her, but she's already told me she doesn't like me. I don't know how I can just suddenly disappear away from her without giving her a reason, because we talk literally all day and share everything about ourselves. I don't know what to do but I feel so drained and it hurts hearing her tell me how she's having the best time with someone who barely spends time on eher, or even shows an ounce of care. Also this has happened to me before so please any advice on future relationships would be helpful.
<bot>: Have crush on best friend, she doesn't like me back. Recently she made out with this guy and is moving forward and I feel terrible.