This 18 year old kid (no offense) has shown more maturity and composure in his 5 lines of text than you have in the short story you just wrote.
I just have to ask this, what would you have gained/lost by simply letting her slide into your lane? So you flip her off, flash your lights maybe even honk your horn but in the end who the fuck cares? Yeah so she's an impatient bitch in a mini van, do you know how many of these people are in the world, what are you going to do chase them all down? This is how road rage spirals out of control, situation's like this where all you need to do is step back and say "what am I fighting about"?