I had a contract of sale signed and now I'm being accused for pressure forced in signing...What can i do?

First, you can fight the lawsuit, if any. The burden will be on the opposing party to prove that the contract was entered into under duress, or some other theory that will make the contract void or voidable. Prior Texas case law has stated the following about duress - "Intimidation will be sufficient if it induces the party claiming duress to perform, contrary to his or her will, some act that he or she is not legally bound to do. The test then is based upon the condition of the mind of the person claiming intimidation. There is no satisfactory general rule that can apply to all situations to constitute duress. Although what constitutes duress is a question of law, whether duress exists in a particular situation is generally a question of fact dependent upon all the circumstances surrounding the situation." - Meaning, that it will be a case-by-case basis.

If the contract is voided, then there probably will not be much you can do to stop the sale, unless you have some other grounds for claiming that you have standing to dispute the sale.