Tax Treatment of a capital loss

A client X owns their company 100%

X had a friend who set up a business two years ago and the friend needed a bank loan. The bank wanted security and out of friendship, X acted as guarantor.

Unfortunately the friend's business failed and now the bank have come to the guarantor for payment.

The agreement was originally between X's own company and the friend to pay the loan. Therefore if the company pays the loan off then that is a capital loss for the company . BUT what if the company does not pay it and X pays the bank back out of her own money, then who is treated as having the capital loss.?

I would have thought it was the company still and a Directors loan account created.?
Could the loss be treated as X's own capital loss?

Incidentally if it is a company loss then is this just c/f if there are no company gains on which to set it against.?

Thank you for any help
david