Seller backing out of a signed contract in Texas

[Viral Mehta]

I signed a purchase agreement for my first investment property in Texas - the original closing date was early April. I paid my earnest money on time and have my loan ready to go. However, it turns out that the seller's LLC was unregistered as they had not paid their property tax on time. They asked for a 2 week extension that I granted. Now, the 2 week extension is over as well, but the seller now needs another 5 week extension.

I am fine with extending it further as far as they are willing to pay $1K for my interest rate lock extension. However, instead of paying $1k and extending the contract they are offering my full earnest money back. Given, how much time and energy I put into this - I do not want to back out of the contract and release them.

What are my options here?
1) Can I cloud the title in some way or can they let the contract just lapse and then turn around and sell the house to someone else?
2) Can I legally force them to sell the house to me?   

Thank you for your help. 

PS: The contract is a standard Texas purchase agreement for a single family home and it says: "If Seller fails to comply with this contract, Seller will be in default and Buyer may (a) enforce specific performance, seek such other relief as may be provided by law, or both, or (b) terminate this contract and receive the earnest money, thereby releasing both parties from this contract."