so I've know this girl for a while. I know that she was really jealous with me and my ex-girlfriend, but (hence the ex) she broke up with me. we've been talking a lot, and she's a horrible texter. you know the kind: short phrases with no emotion. boring to read. but she still sends me smiley faces, which she doesn't send to anyone else that I know of.

I was asking her if she wanted to hang out with me and some other friends, and at some point she said "I have a bf!" to which I responded "well then invite him! I told you you could invite some friends too"

after I found out she had a boyfriend, I decided it'd be best just to leave her alone and forget about it. but then she starts texting me out of nowhere again! idk what to do.

about the boyfriend: he's a football player. could definitely kick my ass, but we're kind of friends.

I was in a very similar situation, it is all about what you want and how far you are willing to take the risk.
Make sure she knows where you stand, be subtle about it.
Remember, have fun! Don't take things too far (which is what I did).
Take her out a couple of times and show her a really good time, take her for drinks or something not too threatening, once she is comfortable enough, ask her out to go clubbing and tell her to bring her girlfriends (that work miracles for me).

I'm even more confused. when I asked if she was going to join me and my friends she said no, but we still talked until about 12:30 that night.

Don't talk to her too much, because you are just putting yourself in a place you do not want to be. Just let it be, call her or text her when you want to invite her out, other then that don't even bother. It's not your job to comfort her.