a civil action lawsuit has been filed against us(my brothe and I)by our lender, what should I do?

When you don't pay the property taxes, the taxes can become a lien against the property and then the lender gets concerned that someone else is going to get paid from the property before the lender gets paid.  you should contact the lender and find out if you are eligible for some type of loan modification or re-finance that would bring the monthly amount due down.  Incorporate the payment of taxes into the loan payment so you are paying a little bit each month instead of having to come up with the quarterly payment.