First time leaving my baby

I have to go on an important work event tomorrow and it's the first time I am leaving my 4 month old baby. I have exclusively breastfed him since birth, direct latch, but I pumped some milk for tomorrow.

I am so anxious. What if he doesn't want my frozen milk? What if he gets nipple confusion and won't drink from the bottle? What if he won't sleep without me?

I'll be gone for just 10 hours but I feel terrible. How was your experience leaving your baby for the first time?