A friend used my computer to hack an ex Facebook and yahoo mail?

[Dylan]

I'd recommend downloading Malwarebytes to remove any infections on your PC.

Malwarebytes Download: http://www.malwarebytes.org/mwb-download/

Once you have it, run a full system scan as well as a flash scan.

This way you will remove any infections from your PC.

After you have removed any infections, change all of your passwords to a new password.

Try to make your new password as hard to Crack/Bruteforce as possible.

To generate a password that is difficult to Bruteforce, go here - http://strongpasswordgenerator.com/

This way, the hacker will no longer be able to see your new password because all infections have been removed from your PC.

I hope this helps.