Contractor threatening lien & charged 4x the estimate on invoice!

[Jennifer A.]

I hope this is the right forum... really need some sound advice, especially if you're a real estate lawyer or have been burned by other contractors.

We hired a contractor to do a small job in our bathroom. We've worked with him previously so he was comfortable agreeing to $490 to do the work. He then sent us an estimate via email, but no contract, despite us asking for one. 

2.5 weeks later the job isn't complete, and when we told him we can't wait any longer and will complete the work ourselves, he called us ungrateful and threatened to file a lien. We got him on the phone to calm him down (against all pride and ego), and later that evening he sent an invoice of over $2,100! The invoice charges us for work he DID do, but we did not expect to be charged for. In other words, he told us he would be willing to do the work but didn't tell us it would cost X, Y, Z. We assumed (wrongly I guess) that it would be included in the original price of $490 or that he'd explicitly state "it will cost me this much to do this extra work" so we can agree upon the new price.

We haven't spoken to him since he sent the invoice, but I can only imagine his thought is that if we refuse to pay that $2,100, he'll file a lien or take us to court. 

How can he do such a thing when we have an original estimate, a verbal agreement, and email threads showing he would do the work for the original agreed upon price? We DID ask him for a contract before work began, but never received one. What should we do?

We're more than willing to settle on a price with him to get him out of our lives, but I'm truly afraid after yesterday's conversation that he'll be unwilling to budge on the price resorting in us all going into legal actions over such a small project.

Thanks in advance!