she started crying a little and wanted to leave but i tried to keep her in my room because we always solve problems by talking right after

Yeah, this is far from okay. If someone wants to leave, you have to let them leave.

one of the first things I said were "did u use that special pass that you said that you had?" (Jokingly because i thought she didn't because she said she woudln't.

That's what you get if you're playing mindgames instead of simply honestly communicating with each other.

While my mother was calming me down with the worlds of i need to think it over night and that it's not that big of a deal.

Ehm, what? Kissing is cheating for lots of people, why does your mum minimise the whole issue?