deep shit

i am 22m

I was on this sex chat website and an user gave me her tg to msg her,I messaged her and she and I both agreed for fun..She sent her selfie and asked mine,I sent my selfie.
she then sent her bikini nude and idk why the hell I sent mine(yes my face is not visible thanks god)
now she put all of that in the post and tweeted and sent me message of the post saying that I am a pedo and should be arrested.
and she is asking me 20k to put down,,,I didn't payed,but yes I am not replying..

and I don't do these shits,its my first time and I am deeply fucked up..
Idk am I a criminal..??

i went to cyber station,they told to come tomorrow morning..plz help..say what is true,I need to hear..