You may need to seek professional help from a qualified accountant.  Generally, there will be recapture on some of the business assets depreciated.  And this will determine the amount of the gain incurred on the sale.  

Click the link for the calculator below that can help determine your capital gain and can provide an estimate on how much tax you need to pay on the sale.  Do not use any commas in your numbers.

https://apiexchange.com/capital-gain-tax-calculator/

I'm very sorry for your loss.