GA - Tenant Broke Lease and Left Without Paying Rent

[James Sun]

Tenant informed me on the 2nd that he would be breaking his lease this month and leaving on the 8th.  He also mentioned he would pay Feb. rent at a later date.  

He sent me a text on the 9th that he moved out and left the keys and garage opener on the counter.  I did a walk through of the property and got a quote of $1850 for cleaning, repairing a few items and painting some areas. 

His deposit was $1800 so that covers the rehab work.  What should be my next steps in order to maximize my chances to collect the lease break fees and Feb rent?  He stopped responding to my calls, texts and emails.  I will send him a certified letter (to my property address) with the final move-out form and breakdown of all fees.

He had a good white collar job with decent income when he first moved in - $6400/month.