If you'd moved on you wouldn't be calling her your crush and this thread wouldn't exist. Your whole attitude is weird, you don't treat her like a friend. Who thinks 'Ah, this would be a good opportunity to be come better friends with someone I've been calling my best friend for the last 4 years'? That's not the thought process of someone who just wants to hang out with a friend, nevermind their 'best friend'.
When I'm hanging out with my best friends it's such a casual affair that stuff like that would never come into my head, and I assume that's the same for most people. Like 'I'm trying to take full advantage of the friendship' is such an alien thing to me. We just hang out, we don't think about the meta of our friendship, which is the only way I can describe your behaviour.
I also think you're trying too hard with Gaf. Your whole 'Oh hey guys, sorry I haven't had time to reply, I've been too busy having an AWESOME time with this super successfully and totally platonic friendship. You guys are such jokers, nice replies bros. Let me tell you about just how AWESOME things are going right now' spiel. I don't think anyone is buying it, but I'm still undecided if this is a troll 4 years in the making or if you're hiding the reality of the situation because you don't want to admit that everyone who told you this was a terrible idea is right. It's one of the two though for sure.