If you can not agree on the sale you can file a petition to partition by licitation, which means it would go to sheriff's sale and be sold by the sheriff and the proceeds divided by the court according to ownership interest. Since you own such a small share, your aunt could bid in the value of her share and buy your interest out for the price of her interest. Alternatively, she could bid very low and get the property for just what she bid without it being sold at full value.. For instance, if the value was $100,000, she could bid 20,000 for the property at the sheriff's sale and if no one bid against her she would buy it at $20,000, she would have to pay 25% of that amount or $5,000 for you share and then she would own 100% of the property. You would receive your $5,000 less the sheriff fee instead of $25,000 which would be 25% of the actual value. The cost of such a suit would be about $2000-$3,000 which would have to be advanced.
Every situation is different and you should consult your own attorney to go over all the particular facts in your case. The answer given is only intended to provide general guidance regarding rights and responsibilities.