2-month-old sleeping through the night and I'm somehow MORE anxious

Okay so this is apparently a good problem to have but like... my son decided last week he just wants to sleep 10 hours straight now. Which is amazing! Except I'm lying awake the entire time convinced he's not breathing. I've checked him probably 15 times last night. My wife finally told me I had to stop or I'd lose my mind. But how do people just... sleep when their baby is sleeping? That's not how my brain works apparently.