No you don't have to get rid of your authentication or change anything other then the members entrance links - which should now go to www.ticketsclub.com. Your members must log in there and then they will be redirected to your members page where they will most likely have to log in again (but if they have an older version of IE it might be seamless).
i.e. if your members page is:
http://www.thegreatestpaysiteever.com/members/
Then send your members to:
http://www.ticketsclub.com/
They will log in there and be shown a list of sites they have subscribed to via ticketsclub. If they are still interested in logging into YOUR site they will click on it and be redirected to:
http://username:
[email protected]/members/
hope that's clarified.