Be patient with yourself. You'll eventually get the confidence to drive further and further. But also be realistic in your expectations. Stick to routes you know. Plan your routes when you're going places, so there's less of an element of "unknown".
I have huge anxiety around driving. My life revolves around a 20km radius that I don't often venture out of. When I do, I become extremely anxious. My anxiety is about getting lost, not so much about a fear of injury or harm.
What is it you're afraid of?
"In the depth of winter, I finally learned that within me there lay an invincible summer."
- Albert Camus
"Everyone wants to get out of the rain
Wants to be free, wants to see no more pain
We're guaranteed that the season will change
'Till then, I'm keeping sunshine on my brain"
- Mike "Eyedea" Larsen (RIP)