Dissolution Decree/Mortgage Assumption

hello, my domestic partnership was officially dissolved in california in june 2009. as part of the dissolution agreement my former partner signed a quit claim deed last year which transferred ownership of the house from both of us to me as my sole and separate property. my responsibility was to either do a loan assmption or refinance the mortgage by november 2010. i just found out today that my loan assumption was denied. i have made all payments on time and have a very secure long standing job as a federal employee. however, my credit-to-debt ratio isn't very good, which brought down my credit score to 640. i would like to keep the house; however, i fear that i may be forced into a short sale. what are my options? thanks!