I don’t understand this; you did it. There is no going back. Sex is a normal, harmless thing that people in relationships do. As long as you’re safe, you are fine and there no need to feel crappy, and make him feel crappy. It’s simply not fair.
If you need time apart, then take it. Because your relationship is not in a good place right now if this is the stuff you’re going to continue to say to him. Process your emotions for a few days by journaling, talking to a trusted friend, etc.