Traumatic incident from leaving kid in nursery

I registered my kid for prek last week. I'm a nervous wreck because the FIRST AND ONLY TIME I let a stranger watch my kid was 2 years ago when he was 2. I left him at the church nursery and he and another kid ended up walking out of the church by themselves. It was a miracle that the preacher was late and caught them in the parking lot. This church is by the freeway. I had a meltdown when I was told a week later (yes they handled it all sorts of wrong...). I never came back.

I've never ever had a stranger watch my kid after that. I was literally traumatized. I still get triggered when I have to drive past the place sometimes. And now with leaving him at school, I feel like I'm being triggered again. I know him going to school was eventually going to happen, but I feel I could get a panic attack or something. Help me feel better??