I got a B+ during my freshman year and I am extremely worried that it will affect my Ivy League applications. I have always been a very studious student and looking back at that letter terrifies me. It bothers me so much that I sometimes have dreams about it and they greatly unsettle me. Will this look as bad to colleges as I think it will? I have had my eyes set on Harvard and it is my dream to attend there
Edit: I am also privileged enough to go to one of the top private schools in the United States and I’m in the top 10 in my class of about 120 people.
No. If you get rejected, I doubt it will be the result of a B+. In the meantime, expand your college list beyond those that reject 95% of its applicants.
There are other schools that are as good as Harvard. A B+ is a B+. If grades other than As directly caused rejections at schools such as Harvard, these schools would have some serious problems trying to fill their freshman classes.
Anxiety like this, though no doubt caused by your environment, is problematic. You cannot live your high school life geared to the goal of getting into the Ivies. It really distorts your experience, believe me. Please talk to a counselor if worrying about a B+ is causing you to lose sleep. High pressure private schools can skew your perspective, Try to educate yourself, or ask your guidance counselor, about the many great schools out there (you can start by looking at the Colleges that Change Lives website)
You’ve got 3 years of high school to go. Get off this website, and focus on your studies and extra curricular activities, and don’t come back till junior year. There’s no need to stress yourself out like this. I had 4 Bs on my app and got into multiple ivies. There’s absolutely no need to fear a B+: your perceptions are skewed by the range of high performers on this site. Also, look beyond harvard: there are many wonderful schools out there that aren’t ivies that will provide you an equal, if not better, education and undergraduate experience.
Private schools tend to brainwash kids into thinking that they’re supposed to get into an ivy league or some sort of elite private school. It’s all a big distortion. The reality is that 99.5% of the workforce run the world’s largest economy without ever looking at an ivy league school. There aren’t enough elite schools for employers to even care. Most are small/midsize companies and it’s more cost effective to hire locally and regionally. Seriously, stressing over a B+ is not healthy. Go be a teenager! 
You’ll be fine. Develop other parts of your application! There’s a reason why the average GPA at Harvard is not 4.0. L)
Let it go and have fun with your passions!
I wouldn’t worry. My kid got three “B-” grades in the course of their high school career and was admitted. The college looks at overall performance, trends and performance. You don’t need a perfect “A” average.