I'm mad at my boyfriend about STDs.
What are you mad at him for specifiically?
I caught him cheating on me and now I'm worried that he will give me one.
I can certainly understand your concern and why you are angry. People should discuss sexual diseases with each other in order not to spread them. You need to talk to him about what he is doing and make sure he is being safe.
I don't think I should have to talk to him. He's the one that should apologize to me.
It's reasonable to expect an apology from him, but you'll have to take the initiative if you want to safeguard your sexual health. If you wait for your boyfriend to bring it up, you may be putting yourself in an unsafe situation. Don't engage in sexual activity with him until you've both discussed his sexual health.