Not knowing the terrain etc. you might have other options. You said your wife was armed, so I assume she has had training and knows how to shoot. And she has a cell phone so she has called 911. Now is there a big tree as close to you as the car? If you go back to the car if a firefight is a given, you are going to draw the fire to the car where even if he misses you he may hit a family member. Of course I dont know the situation. If you were behind a tree could wifey start backing the car up and you safely make your way through the bushes and meet her at the closest safe location? 911 and police are on the way. If you mention shooting the police WILL arrive quickly.
I was involved in an indecent, I came across a person had been shot on the roadside, Remote location, I called 911, mentioned shooting and the Sheriff must have driven 100 MPH to get from where he was to the location we were at. Followed within minutes by a swat team, ambulance and ultimately a medivac helicopter. In the end it was discovered it had been stupidity, a person had set up targets in some brush, No background and the rounds were going across a road which is where the person got hit. Police caught them. A couple days later I was asked to give a statement which I did. I asked what type of gun it was and it was an FN 5-7. It was quite exciting to say the least and the person survived, Had been hit 2x.
Interesting thing if you ever find yourself in this situation, There was almost zero blood, if the person had not said they had been shot you wouldnt know it. All the bleeding was internal, externally the entry wounds just looked like 2 small welts.
I read in the paper a couple years later all the guy got was 10 hours community service and lost their hunting rights for 2 years. It was reported not 1 hour after he was sentenced he stopped at a gun store and tried to purchase several guns but got stopped by the background check. Some people are just real losers.