If you put stop payment on the check, then the management probably had a valid reason to refuse to accept a payment by check again for payment. The initial payment was simply for a security deposit. They could have required for you to pay the rent in cash or certified funds, because of the stopped payment on the check. So, yes, it is possible for them to sue you for the rent and the late fees. However, the problem with the bedbug infestation might be a possible defense to the payment of rent. You need to sit down with a good landlord/tenant attorney to discuss your options.