quitclaim

i purchased a property from a friend who owed me money, in fact it was money loaned so she could buy the property in question, we came up with an agreed price but renegotiated several times due to the condition of the home, the home had been vacant for years... it was a private sale and i agreed to pay her a small fee monthly, the back taxes and the payoff of her loan, all this was done and it was quit claimed to me, now she wants more money, disagrees with the agreement and is threatening to get an attorney and repossess this mobile home. i am concerned because all the paperwork that was renegotiated is not available because i deleted it off my computer, and the balance is almost totally paid, it was a private sale!
which is why she quitclaimed it in the first place, i believe she feels duped, and has lost her mind, i mean can she really come after me since i feel the balance is nearly paid, and she wants to up the price , i mean its been years!