Last summer, A girl told me she loved me on Snapchat because of some circumstances, and I told her I was gay on Snapchat... I never knew how she reacted, I just know she didn't like it. After coming out to her, I felt really good about coming out to everyone, until I went back to school. I feel really anxious around any person in her family, which includes her father, our gym teacher, and her mother, a teacher I had last year, but still regularly see. I want to know if coming out to everyone will make me feel as anxious as I am now around her family, but all the time.
Coming out to everyone is a bold step. And it takes a lot of courage. Once you do that, however, you completely give up control over who knows that you are gay, and whatever people might think about that and about you. It's rather liberating if you can reach the point of no longer caring what people might think. The anxiety goes away as long as you can be out and proud of yourself. Of course this works better if you are in an accepting environment - so think carefully before you decide to come out to everyone because it can't be undone. Overall, for me, it has worked out well. But I'm also a 48-year old man who is not dependent upon other people for my ability to live safely, earn a living, and live life the way I want. Good luck!
Speaking from personal experience only, my anxiety (in general) and shitty feelings about myself REALLY improved after coming out to most people. But like said above, the more people you tell, the less it is in your control. Although my anxieties overall have greatly improved, I still sometimes get super anxious when my friends are around my parents (because there is nothing beside human decency from them outing me).