I share similar fears to you when driving. I hate it when big trucks drive past me. Some things I do the next time driving after something that scared me is to avoid busy streets and have some cool air blowing around the car along with playing music that I really like to help keep me calm and focused.

Honestly... when you're driving it's the other people you have to look out for! I'm sorry to hear you had a bad experience due to someone else's recklessness. What helped for me was getting a dashcam, so at least if anything happens I'll have proof I drive carefully. Also having stickers on your car like the "smile you're on camera" ones may deter people from driving erratically around you. For calming your anxiety I'd also recommend listening to some music you like whilst driving. You could also research any routes before setting off, especially as they can show live traffic and road closures etc which may make you anxious if you're unaware beforehand.