Im sorry to hear about your troubles, and i hope this illbehaving exfriend gets what he deserves for ruining your gameplay and costing you more money on the side.
But as for sharing account with a friend, i see nothing illegall or wrong with it... and i consider FC´s policy for it to be stupidity.
Whats wrong with sharing account with a friend you trust?
I´d say its in the hands of the account holder to decide if they have trustworthy enough friends to give their creditcard details in hand. (as this same password does control your subscription too)
But, for gameplay id say it helps alot to have a friend´s account on handy and viceversa.
Offcourse many players have multiple accounts for themself, but for those who cannot afford the time&money investment for it it helps to have this kind of access to additional account...
If id get banned for doing this, what clearly does not meet the criteria of criminal activity, i would pursue FC for fraud. Fraud criterias meet when customer has paid for services for sometime onwards and FC bans the player for EULA violation, minor like this one. FC cannot prove it to be serious offence, discriminated action of one or many parties.
So, customers right code would rule for favour of the customer...im pretty sure of that.
And if that would not happen, i would just head to FC´s office and kick the sheit of every pencil neck there