You feel like you have to be there for her????? Who is the therapist and who is the client in all this??
Am I understanding this correctly - you have leant her money and you are worried that if you terminate then she will never pay the loan back?
I think you know this sounds a bit wrong. I think you should see some other independent person and let them know the full story and ask for advice - either a different therapist or the body that regulates licensing in your area. You don't have to give any names for you to just inquire.

You have gone to therapy because you have problems and are extremely vulnerable - it is very easy for someone to take advantage of this. This makes things extremely hard on you. Remember, you are the MOST important person in your life, you need to look after yourself, not worry about people who aren't even your family or friends. Do what you think is right for you.