3 weeks pregnant and afraid of something going wrong

I am about 3 weeks and 6 days pregnant. I am so afraid of miscarrying or something going wrong. I want to be excited and happy, and while I am, I am also horrified that something will go wrong. Has anyone else felt like this? Does anyone have an reassuring word, success stories, or anything helpful to share with me? I am also afraid to tell people about the pregnancy because of the fear of a miscarriage. My husband's family is coming to town this weekend and he wants to tell them then but I'm really afraid to. I don't want everyone to get their hopes up and then have something bad happen and have to upset everyone with the news.