Hi @Platwooo ,
I’m so sorry to hear that you’re feeling like this. You’re not alone- many people in this community felt shocked and scared when they first learned they had hepatitis B. BUT- it won’t feel like that forever 
. If you can learn about hep B, you’ll find that you become more used to the idea and it will worry you much less. People with hep B can live long, healthy lives and it sounds like you have a good doctor to guide you.
About your main worry: there are simple things you can do to protect the people around you. The first is to know how hepatitis B is spread, and how it isn’t. Then you will know that you are not dangerous to other people in most situations.
I don’t know if your doctor has given you any information yet, but here are the basics: hepatitis B is NOT spread like the common cold, or like a stomach bug or food poisoning. So, breathing, sneezing, eating, touching people, hugging, kissing are safe. You don’t need to worry about any of those.
Instead, hep B is carried in the blood, and some other body fluids. Your blood would need to get into someone else’s body, to give it to them. This is not something that happens easily! The most common ways are during childbirth (called mother-to-child transmission or vertical transmission), during medical or dental treatment, or some kind of injury where you bleed a lot, or during sex. There are others, but those are the highest risk ones. For more information, I would recommend you use a reliable health website like this: Hep B Transmission | How Do You Get Hep B | Hepatitis NSW
The other really important thing to know, is that there is a very good vaccine for hepatitis B. If people have been vaccinated and their bodies have responded well to the vaccine (more than 95% of people vaccinated), then it’s almost impossible for them to get it. They are safe. If you know who among your friends and family have been vaccinated, that might also help you to feel less worried.
About telling family and friends: this decision really depends on you and your circumstances. Different people in this community have had different experiences. Most would agree that you should tell any sexual partners, because you might have given the virus to them. If that person has been vaccinated, they are probably protected, and they can get a blood test to check their body has made enough protective antibody. But if they are not vaccinated, they should be encouraged to get tested, and vaccinated.
In my personal opinion, though, you don’t need to rush to do this right now. Give yourself a few days to understand what has happened, learn more about hep B, and let your emotions settle. For that kind of big conversation, you should be prepared, calm, and have the right information.
The Hepatitis B Foundation (in the USA) has some very helpful information about this: Disclosure: How to tell your partner, family, or friends about your hepatitis B or D status: Tips and tricks - Hepatitis B Foundation
We are also here to support you as you think it through. Other people have had these discussions on the forum. Lots of them are under “Living with hep B –> Relationships” tags. Relationships - Hep B Community
Hang in there. 
