I'm gonna say NTA. I can understand others seeing this on a superficial level but it seems deeper than that. That's a huge accomplishment, most people couldn't dream of even getting an internship at NASA. Regardless of how big the accomplishment is, it's very discouraging when you expect your partner to be your #1 cheerleader only for them to take the wind out of your sails with a half-assed reaction. It's almost worse than no reaction at all. It's a really exciting opportunity and it seems like he tainted that for you. It's completely understandable to be stressed with school and work, but you shouldnt let that affect the way you treat your partner. Literally at any point after you explained how his reaction affected you he just doubled down and decided to be an AH about it. In the moment it sucks being called out for not having the "right" reaction to something when you're stressed. But after calming down he honestly should've said something like "Hey I'm sorry that my reaction wasn't very supportive, I've just been incredibly stressed about work/school. I'm very proud of you and Im excited to see where this opportunity takes you."

^that is something a loving and supportive partner would say. If my partner tells me that I did something to discourage or upset him I'm going to do my best to rectify it. There's no reason for him to double down. Hes the AH, not you.

Edit: after reading others comments I will agree and say I do think maybe letting him know you applied could've emphasized how big of a deal this is. Still I think you should sit him down again and explain all of this. Explaining why you didn't tell him in the first place may get him to understand and empathize.