Fear of being arrested

So what went down was, as a juvenile I was been In a lot of trouble.
I have been arrested in the past and charged with big indictable offences, this brought huge distress and I was panicking through out the entire process.

What has recently happened was between someone online.
I had told them I 'Got someone to kill them' (Jokingly) they had claimed to reported me and said I would be extradited and face charges, however after a week they made it clear that they didn't report anything, but even after this being said I am still in fear for some-reason. I have been obsessing over it for over 2 weeks now, which has caused huge distress.
How do I overcome this. I have been having nightmares about being extradited and having my life ruined.
Thank you