If my buyer fails to complete, forfeiting their deposit, can I decide to keep my property and not proceed with a sale to ClozeSure?

Yes. You are not obliged to trigger ClozeSure. You can decide to keep your property, or put it back on the market. 

Yes. You are not obliged to trigger ClozeSure. You can decide to keep your property, or put it back on the market. 

Note that you will not be entitled to a refund of the ClozeSure fee.