In need of immediate relationship advice?

Okay so I met this girl on wednesday and we immediatly started dating that night. Now I'm not really good with relationships for starters, especially with strangers. She's nice enough and cute but I can't help but think she bugs me at times and we've been dating for four days.

So heres the problem, I go over my friends house and she tells me this cute girl cheats on people. Then she says her hot friend who I'd met months ago wants to talk to me. Hot girl is wayyyy more attractive than cute girl, but I don't want to hurt cute girl. Cheating is out of the question, I don't do that stuff. But now I can't decide what to do because hot girl is flirting with me, and she doesn't know I have a gf. I want to get with hot girl, but I don't want to cheat or hurt cute girl but I also don't want to stay with the cute girl and lose my chance with the hot one. I'm thinking of suggesting that the cute girl and I maybe were taking things too fast and I wanna be friends first or vice versa with the other girl. Help? What do I do I have not had a relationship in over a year and have no Idea how this works I am 16 btw.