When you have done everything but gone out the door, set your next goal as the first thing after going out the door. e.g., going down the road to the bus stop.
Tell yourself that opening and going through the door is just the first part of that action, and focus on the bus stop.
Tell yourself that you ARE going to the bus stop, and then take your mind off the door part by thinking about the route to the bus stop, possible neighbors you might see, etc. OR, focus on something distracting, like music or an audio book, while you go out the door.
If you feel panic about some of the pressure, try focusing your attention on you breath. A good way to do this is to breathe in through your nose and out through your mouth. Pay attention to every sensory aspect of your breath and you focus on the anxiety issues should diminish. Try vipassana exercises if you can learn them.
If you can refocus your attention off your anxieties while you physically exit the door, getting the rest of the way there should be much easier.