My old classmate asked me to hook up and when i declined she went insane, what do i do when we inevitably meet again in a group setting?

So basically me (16M) and this girl (17F) were in the same class because i am 1 year forward.
In my school system there is just 1 class, and ours is small, counting 16 now.
We are a pretty tight group where everyone is friends and apart from school related stuff there aren’t any arguments.
Back then she left because she had a massive argument with the group because she kinda threw the class under the bus for a political move.
That and academic pressure made her leave.
Back in January when i wasn’t in school she texted that she missed me
She kinda texted me through the year but nothing major.
Now in June she started texting me A LOT
And sending me romantic posts
I wasn’t in love with her so i ignored those or replied awkwardly like wait for the right person or stuff like that.
Well she started sending a LOT of those every day.
And i cut down on responses hard
Generally just reacting to the message with very vague emojis or just straight up not responding to that kind of messages.
Well one night she started to drunkenly text me
Saying she was out
I could see where it was leading so i told her to have fun and live the moment
She didn’t or didn’t want to catch the hint (like the past 2 weeks)
So she started saying shit
At some point she said “Vallelunga is a date idea”
(Vallelunga is my home track where i do motorsports photography often)
So i said “yeah with Cris and Mizzi” (2 friends of mine)
i sent a photo of us 3 she replied “how hot” and said “take me there on a date”
I replied “no”, so she said “why not?” i simply said “sorry i am not feeling it”
She stopped texting me for one day before she started again.
She was the SOLE person sending me videos, initiating conversations at this point.
A few days later she texted me at 9 in the morning “everyone i know fucks”, “i wanna fuck” to which i replied “give it time” (which i realise is ambiguous a bit but i feel that i shut her down already) to which she replied “want to fuck”
I said “no sorry”
To which she replied “what do i miss that the others have” i replied “nothing, i simply don’t have feelings for you, the right person will come along”
She replied “ok bro”
She stopped texting me for a few days before she went on a rant about how she was sexting a French guy and he was so much better than me and i was unfuckable
I just replied good for you and left it at that.
The issue is that she is still integrated in the class group and we are still active
The next hangout she will probably be there
I don’t know how she will act and what to do.
My guess is she never cared about me she just wanted easy sex, im a tall guy for any age at this point (192Cm ~6.3-6.4 for you americans)
I am not a chad but neither a chud
In fact i was shocked that she texted me at all
as something of this matter never occurred to me
TL;DR Ex classmate asked me to hookup, i turned it down and we will meet again in a group setting, what shall i expect and act like