We have a form at https://scamsurvivors.com/romance/form/form.html
that you can fill in regarding romance scams. Please put as much information as possible there. Once completed, a member of our staff will contact you for advice, more information etc. This is usually within 24 hours, but may take a little longer. Rest assured your form won't be ignored, unlike certain other places.
This form is only for romance scammers. For sextortion, go to http://www.blackmailscams.com
and for 419 scams go to https://scamsurvivors.com/forum/viewtopic.php?f=6&t=68230