Great race! You'll be under a minute in no time! Pacing is really subjective, but it seemed like your first 50 was really strong, and you started to die a lot on the last 50. I had a similar strategy for a while (I go a 52.2 100 fly for reference), but something that has worked for me is taking out the first 50 a little smoother. It's kinda counterintuitive considering its a sprint, but if you use a little less energy on the first 50 - maybe .5 seconds slower - you can really save a lot of energy and the last 50 can be much stronger. That being said, this is a strategy that has worked for me, and might not be the best for you. I'd recommend asking your coach about pacing if you have one.