<human>: Hi reddit,

My gf and I were looking for temporary housing for 2 months, because we were looking to move to a nice apartment that starts 2 months later, and our current lease was ending. 
We found on craigslist a couple that were also desperately looking to move out because they need to relocate to Dallas for a job. Since they needed to sublease out the apartment unit, the rental office said they would have to give up their security deposit of $500. 
We decided that we would just write them a check of $500, and we would get their $500 security deposit once it was up.
We decided to take the apartment.
Everything went smoothly up until I went to sign the lease. I signed the lease, and gave them a check of $500. After leaving for five minutes, the rental office calls me back and tells me that there were others looking for the same apartment unit. Apparently, the couple had looked for other potential tenants behind our backs just so they wouldn't lose their $500 deposit. This confused the rental office and me. We called the couple several times, but they wouldn't pick up. I was really frustrated as they were about to jeopardize our spot in the apartment, so I decided to cancel my check.

A month passes, and the couple emails me from Dallas demanding me to write another check to them and that it's a criminal offense in this state (Minnesota) to bounce checks. I didn't sign my check intending to cancel it, I just changed my mind because they decided to screw things up and ignore us afterwards. 

Am I legally obligated to be writing them another check?

Can you summarize the given text in a few sentences?
<bot>: I cancelled my check because the other party didn't follow through with their end. Now they're emailing me that they want a check, and they're scaring me by saying it's a criminal offense.