Personal loan

Hi,
No, sorry, I am afraid you'll have to pay the interest as well.  The reason is simple: 1000 $ today and 1000 $ in 2015 are not the same.  If you want to compare two sums of money of different dates you'll have to bring them to common bases, and that is being done by calculating the interest (anually - so it includes interest on the interest as well).  So it doesn't really matters if you have an agreement or not (as long as you agree that you owe her the sum she claims and the dates you received the money). 
Best regards,  

Hi,

    You benefited from borrowing money from her.  I think you should go to a bank and see how much interest they would normally charge you if you borrowed the money from a bank.  I honestly think you would have to pay for a certain interest because if she invested it somewhere, she would have made money on her investment.  She was very generous to let you borrow from her, thinking that perhaps in the future, if you married each other, she would have benefited from it.  But since she is your ex, then you should be a gentleman to pay the money plus a reasonable interest.

I read your question about the $8,000 you owe your fiance.  I don't know what state you are in but different regulations apply in different states.

One would think that if there is no "written agreement" (which in the future, make SURE you do), and there was no discussion at the time of your receiving these funds, then it is quite likely that the issue of interest is mute.  However, she did help you when you needed it.  Giving her back some extra funds when you pay her would be the right thing to do.  She helped you, show her a little appreciation.

Had you actually taken out a loan, you would have had to pay interest.  Give her a few hunder dollars in addition to the $8,000.

OK, the above answers are about 1/2 right.  In CA, and most jurisdictions, there are prejudgment interst statutes that start interest ticking on any money you owe someone but have failed to pay (unless a written agreement is to the contrary).  The clock doesn't start ticking, however, until the money is due and owing.  So, if she loaned you the money on day one and did not ask you to repay the loan until 2 years later, the interest on the amount starts being calculated on the day you are supposed to repay the loan.  If there was no specific date on which she asked for it back your best bet is to calculate it from the date you two broke up.