the way I see it depending on the situation you have a few options, your
first option is to nip that in bud immediately with some domination and prepare for a battle to put her in her place (this must be done absolutely 100% belief in yourself) without getting angry, or starting to whine about it, be more harsh to her, make her feel like not speaking out against you (this is of coarse if you can handle this)
some canned lines from the memory bank for you would be
''ohhh look its the leader of the gang, do you tell everybody what to do to?''
''you know the shit coming out of your mouth is unbelievable, do you have anymore diarrhea you want to spew from that stink hole?''
''just cause your not getting any guys doesn't mean you should cock block me, DON'T BE A BITCH''
''SPEAK FOR YOURSELF, JUST BECAUSE NO ONE WANTS YOU DOESN'T MEEN THE GIRLS HERE WHO CAN ACTUALLY GET SOME WANT TO LISTEN TO YOUR CRAP''
''shut up, no one likes you''
prepare for a furious argument, if she thinks you are likely to fold under-pressure and she has big numbers of safety around her she is going to come at you like a crazy spider monkey, take note that this option will most likely blow you out from the group you are trying to get with, but that is ok and is not the point of this, if you have to be around this person in the future, she will walk all over you if you don't set the ''DON'T FUCK WITH ME BOUNDARIES'' she has to realize that you are not one of which she can fuck with, without having her rudeness returned in an extremely overwhelming fashion, if she throws a drink at you, throw one back at her, if she hits you, stay calm and keep announcing what she is doing, and how negative it is, statement after statement about her, question after question about her
the trick is detach yourself from the situation and make sure it has no emotional bearing on you, interrupt her and project your voice confidently, don't get mad, just be very clear and very rude, you want her to feel as if when she talks negatively she will be put down and told what to do, focus on her completely if you lose focus and start emotionally reacting you will notice as a side effect your focus will shift internally to your self, you will stop giving commands to her, come off less confident and start qualifying yourself because she is holding a stronger frame, everything is related to ''YOU'', not ''I'', hold very strong eye contact and be dead serious until she starts qualifying herself/apologizes/crys and runs off, never take any blame for anything you say, it is all her fault, everything is on her and has nothing to do with you, you are simply projecting on her no matter what anyone says or does, you don't apologize you are right they are wrong PLOW PLOW PLOW be a dickhead, and if you do this properly, this girl will behave for a really really long time
second option, good old goofy positive re-frames on everything she does,
here are some canned re-frames for you that I could think of for that particular situation you gave an example of:
''oh I get it, you are in love with me but trying to hide it, that is so cute, you don't have to play hard to get, I like honest girls''
''ohhhhh I seeee, so when it is not a girls night out, you all want me

well I knew you were into me no need to make excuses''
''GIRLS NIGHTS OUT ARE ALL ABOUT GUYS, DON'T BE CRAZY, YOU WANT ME, I CAN TELL BY THE WAY YOU LOOK ME UP AND DOWN, YOU ARE OBSESSED WITH ME'' (prepare for random shit test, just counter it with your mom *what ever she says or mock her and say you're cute*)
''DON'T BE CRAZY, I SEE THE WAY YOU LOOK ME UP AND DOWN, YOU ARE PROBABLY THINKING ABOUT LICKING ME UP AND DOWN LIKE AN ICE CREAM CONE RIGHT NOW, WE CAN ALL SEE THROUGH IT, DON'T EVEN PRETEND (same as above alot of variations of this same thing can be used)
''girls night shmirlsnight, don't be weird, you know you love a good time and hot dude, don't even lie''
''OHHH FUCK OFF *playfully*, your like the cute little teddy bear that makes money off hugs then doesn't want hugs anymore, don't worry Ill still hug you'' (then go for hug expect she is going to try to stop you/resist, just keep teasing her for being the grumpy teddy bear who ruins everyone's fun)
''YOU'RE LIKE THE GRINCH THAT STOLE GOING OUT AND HAVING FUNS-MAS, WHAT'S NEXT ARE YOU GONNA GATHER UP ALL THE WHOS DOWN IN WHOVILLE, AND RUIN THE NIGHT FOR EVERYONE?''
''YOU ARE SO RIGHT, NO ONE WANTS ME, IM GOING TO DIE ALONE, AFTER ALL IT IS A GIRLS NIGHT OUT''
''WELL THEN GUESS ILL GO KILL MYSELF SINCE IT IS GIRLS NIGHT OUT, AND EVERYONE HATES ME'' (make sure you do this is a really sarcastic cheeky way and find self amusement in it)
third option, pretend she does not exist, don't acknowledge she spoke at all, for the rest of your night, your job is to continually ignore her, give every single person attention, start conversations, your favorite words to say to her are, OH THATS NICE, I DUNNO, AWW THATS COOL, AWESOME!, OHHH WOW SO INTERESTING, YOU DON'T SAY, and REALLY?,
anything she says or does in an attempt to speak to you directly gets one of those above stock responses, for the rest of the night you are not to speak with her, she is on time out