Withit, have you discussed this with her at all previously?

I would work to think of ways to pay her back in the future? Ask for a partial reduced fee and partial "loan" until you are finished and can pay her "back" -- credit if you will? The British have an interest-free loan thing for "training" purposes http://www.bap-psychotherapy.org/BAP_Prospectus.pdf maybe you can think of some way you'll be able to pay in the future, some way therapy will help you to earn more?

Do you get Christmas bonus, yearly bonus, or tax return, etc.? You can pledge them?

I would start by discussing length of therapy and what you and she have in mind and go from there to cost?