I meet plenty of people who've been on iRacing two months and are still too nervous for a first race. I get it. Those nerves are a beautiful sign the hobby has hooked you. They're not a problem, they're evidence.
The only way through them is exposure. Test drive, open practice, AI session, then race. Don't wait forever. Everyone you're scared to share a track with was a rookie once too.
At the start, forget the other cars. You're racing yourself and the track. Brake straight, ease in, wait, be patient on the way out. Repeat. The lap times come, and the other cars become scenery you don't hit.
Lick the stamp, send it, and enjoy being a rookie. You won't be one for long.
If this side of the sport pulls you in, the longer conversation lives in the psychology section. Sim racing is more mental than it gets credit for.