I drive pretty much every day, and a lot of highway driving at that.

You definitely will get used to it. Even driving 40mph on local roads used to make me anxious, but now I just cruise and listen to tunes everywhere I go. Start slow, get a bit higher and higher, and just be aware of your surroundings. Honestly, your biggest concern is really just the way other people drive. Ask yourself "what's the dumbest thing the person in front of me can do" and just be ready for it. Don't push yourself to go faster than you need to, and be aware and prepared to brake.

And yes, I still don't like parallel parking.