Reassuring my boyfriend

So. My boyfriend n I had sex today but the condom slipped off and he finished inside thinking it was still on(we've been trying to find him a better fit so we tried a new brand, not his fault) I've been on introvale for 9 days but the pharmacist I spoke to still recommended using a plan b to be on the safe side so I did. I figure I'm pretty much good to go now but my boyfriend is still super nervous n upset n beating himself up over it. He's been apologizing all day and I'm now kind of worried that he's gonna be afraid to be intimate with me in the future thinking he'll mess up again. How can I reassure him everythings gonna be ok?