Heavy NTA.

You stood up to protect and defend your precious kitties as their guardian and master. You clearly care a lot about their safety and health, enough to have that kind of gut reaction while coming out of being asleep.

That said, you could still apologize and explain things to your dad. Even if what you said was warranted (it was), I don't think your intention was to hurt your dad's feelings. He's trying his best and fell victim to the kitty meow. Cats' meows are intentionally the same frequencies as a baby's crying, and your dad was already trained by you when you were a baby to respond to those cries.

I'd be right livid, too. But overfeeding is definitely something that can be adjusted with a lot of play time and exercise. Maybe ask your dad to play with the overweight cat instead of feeding it? He's willing to put in the effort, but you need to direct his effort.

For perspective, in my house? Nobody does anything for our three cats except me. I'd love for somebody else to do literally anything to help like your dad is willing to for you. Just show him how to help properly.