The society as in the US society is insane over the issue like no other nation in the world.
Ten years ago is a long time and you likely had junked the computer long ago but if you had it laying around take out it hard drive and drill holes in it and then throw it away.
Deleting files does not mean that they are gone for sure as the delete function only free up the area on the hard drive the files had existed on to be able to be used again, it does not wipe it.
Only when and if that area is used once more by the OS are the files wiped.
Sadly there been cases where for one reason or another someone had found such long ago deleted files and it had cause problems for their former owners.
The odds are great that those files are now gone forever but it is not zero so if that computer is still in your hands it is worthwhile to reduce the risk to zero at the cost of a very old hard drive at least in my opinion.
As far as feeling guilt for looking at such materials out to curiosity so long ago it seems an over reaction to the fact that human curiosity sometime lead us all to do questionable things in our lives.
As far as going to the police and risk ruining your future for zero gains to anyone that is being beyond stupid.
If you feel the need to talk about it I would suggest a license mental health counselor who can help you with your feelings of guilt and who by law must keep the informations you share private in most cases.
The police are not set up to be mental health counselors to say the least.