Depending on the value of the property it might be worth getting an attorney to represent you. From what you said, you both own the property but only one is able to have full enjoyment of it. you need to answer the complaint and move forward with the litigation.
You are probably being sued in a partition action, which is very much like a liquidation since the property will be sold. The biggest issue that you need to be aware of, is that you may be entitled to a greater share of the proceeds from the sale, but you have to make that case with the Court. And, your expenditures need to be very detailed and reliable. If there is some value in the house, and if you believe you would be entitled to more than 50% of the proceeds from the sale, you should hire counsel. Partition actions can be one of the trickier actions given what usually goes on in these cases. Again, if there is some value to be had, you should look to securing counsel. I got 94% of the proceeds for my client in a partition action in the past, so it may be worth your while.