the important thing is to get them out and move on

You shouldn't have let them get this far without paying you in the first place. however since they are ready to move out, I would let them and make sure they don't cause any more harm to your house. Focus on finding new tenants now because November is a tough month. Think of it this way, they lived in your house for 5 years so that means you didn't have any vacancy for 5 years, $3000 over five years is not too big a deal. Next time don't let tenants owe you more than a month. Take action early.

You can still sue them after they are gone, but right now, you want them out without doing damage to your house.