Small claims case regarding security deposit.

Location: Colorado USA.

I am being sued for withholding a security deposit by a would-be tenant who decided not to move in because their landlord changed their mind about selling their current place. One tricky part is that the lease they signed was not countersigned by me and is no longer accessible because it was cancelled between the time they signed and a couple weeks later when the lease was cancelled.

This lease was generated on Zillow, which is why I cant access after cancellation. I have email/text documentation that they did indeed sign the lease although I don't know how pertinent that is without the actual signed lease available and me countersigning. They backed out 2 weeks prior to move-in and I re-listed the condo immediately after learning that they were backing out. I informed them that they would get their money back if I did find a renter within that time frame, but I was not able to. The withheld deposit is it cover lost rental income.

Please advise me on my rights. Court is in 3 weeks.