Contractor threatening of putting a lien

[Sonu Sharma]

Hi, I have worked with a contractor for the last 2-3 years in TX and although he is slow, I stuck with him for convenience and dependability. Although, we have a general contract for any work, neither of us signs it - I pay him as the work progresses. On one of my recent repairs, he left the job midway and is expecting a pay for the unfinished work. I was willing to pay him in a few days but he started threatening to put a lien on the house until I paid him. This makes me think all the mistakes I have been doing......not enforcing a strict contract etc....

1) Does he have a case to put a lien without neither of us signing a contract to begin with ?

2) How long does it last ? Now that he is threatening, can I hold off on the payment until I sell the property ? 

3) Say, I owe him $2000, if and when I pay him upon him putting the lien, how much would I have to repay - I mean, what kind of interest is charged ?

Appreciate your help !