I've just killed the dragon at the watch tower (near start of game). I returned to the king to talk to him about killing the dragon and had my shout active. I pressed R2 by accident and everyone started to attack me.

I can't even escape the city without being killed, to many guards after me.

What's the best thing to do?

Re-load a previous auto-save/hard save.

Immediately draw your weapon and sheat it again.

Draw and sheath your weapon to yield. Or reload a old save.

^ What they said.

Pay your bounty or go to Jail.
If not. Die a horrible death and then reload.

i kinda had the same thing like you, but for me it was after i got Lydia and crowned as Thane, suddenly i went to Arcadia for the first time in the game and there was 3 guys who wanted me dead. I loaded the game and didnt go in there but then i went into Dragonreach and suddenly everyone had a fight where balgruff usually sits, it seemed like the ywent mostly after Lydia as i didnt make her follow me immediately. I have no idea how all this started but im suspecting it was my sneak attempt into the house where you need to find proof "missing in action"

Really weird stuff but i kept on playing after killing the 2 guys out of the 3 from Arcadia out on the whiterun field and some assassin was after me aswell sent from Astrid who i dont even know who is, and some bounty hunter on the road back to riverwood. Really weird stuff and now Farengar hasnt been in the game for 30 hours lol. I just hope i can finish the game without any bugs

but i must admit ive reached a point of fear so ive got like 60 saves so far inb the game after 57 hours of gameplay which kidna ruins the game as you fear u might have to load a 10 hour save back because youre afraid some killer bug will appear.

Reminds me a bit of the quicksaving in games like Commandos/Desperados where you just make it a habit to keep saving

Done it, I got away by jumping around, broke into a house, guards came arrest me so ended up going to jail. When I got out it was all normal.