Newsflash: House purchase question.

I entered into a contract to purchase a property at the listed price. I added a provision that stipulated an increase in the purchase price by $10,000 if the seller accepted my offer by 9:00 PM on June 14, 2024. The seller responded 14 hours after the expiration of the $10,000 provision, indicating his acceptance of our offer price with the $10,000 increase. I am now uncertain whether to proceed with the additional $10,000. Kindly advise.