My ex wife (we are divorced with a separation agreement

My ex wife (we are divorced with a separation agreement signed) received money from a passed away relative. We were together and had a visa under my name that had money owing on it from both parties roughly 10k. The money she had received was split up from the deceased in his will for her, her sisters and her nieces and nephews. She used some money to pay off the visa in order to get approved for a down payment for a house, the down payment was 50/50 all of which was loaned money from the deceased funds. At the time in 2008 I had said verbally I would pay back the 50% of which was 12,500.00. Over the years that was never paid back. The separation was in 2012 and the divorce finalized in 2014. During the years she had paid back money she loaned 7500.00. In the separation agreement it states the home is to be split 50/50 and whatever you have as "your" debt in your name is ***** ***** pay off. I saw that as this money that was used to pay off the visa and to be used as part of a down payment. She had lived in the marital home from 2012 til 2014 with her paying into the mortgage and myself as well. The house was sold in 2014 and we had decided it would be 60/40 in favor of her. In an e mail she requested i use the 40% to pay back this loaned money of which I agreed but don't remember doing so (i cant find the email.) When the house was sold and the money went into the dual account she used the 40% and put it in the account for the nieces and nephews. Most of our conversations has her strong arming me into most decisions with threats of going after my pension. So, i agreed to certain terms. For example, in an e mail it says i'll pay 290 a month because thats all i can afford. I never paid her any payment.She has put a civil claim in that I owe her that money, 12,500.00 with the 40% paid off from the home of 1300.00. total of 11,200.00 plus lawyer/claims fees.where do i stand?