Do u think that she's telling me 2 back off?

So this girl (Cindy) that I thought didn't like me is all nice to me all of a sudden. My crush is also in the same cl. I think that she kinda likes me crush. Cuz my crush is always making me laugh. Like he turns around and says nothing and I start laughing. The other day Cindy kept on asking me y I'm laughing so much and what's so funny? I could c from the corner of my eye that she wanted to know what was going on? Usually when I talk to Cindy she just makes it look like she didn't hear me and turns around and starts talking to someone else. Then I was talking 2 my friend and I said something about boyfriend and Cindy shouted "OMG! U have a boyfriend?" She shouted it out loud like she wanted everyone to hear it. My crush was writing when before she said that and then I saw him freeze when Cindy screamed that. Then I said "No i don't". I'm the type of girl that's very sweet and innocent. So when my crush is being all perverted I say "EEwwwww" and change the conversation. So after cl Cindy starts walking with me all the way to my locker. Telling me random stories of my crush's ex girlfriends. It seemed to me like she wants me to not like him anymore. Do u think that she has a crush on him & wants me to back off? What should I do?