TexaSIG, he in fact did not break the law in Texas. Texas law specifically allows for the threat of use of deadly force if it will avoid the use of force. I can give you the citation if you'd like.
Also, in Texas, the assailant does not need to have had a weapon, rather, you just need to have believed there was the imminent possibility of serious bodily harm. However, convincing a jury is what you have to be worried about. You probably would have lost that one. Better to try to get out of there unless he escalates.
Also, by pulling the gun, you just gave him an excuse to shoot you. If you are not going to shoot, it's probably best not to draw.
And f4t9r, I hope you are kidding. Not only is it absolutely stupid to tamper with evidence, and turn a possibly justifiable shoot into jail time, but who has a throw down gun on them anyway?