I hope that these past few days have brought good news for you. But if you're reading this, there was probably some disappointing news. Perhaps you were deferred or got in EA, but don't really want to attend that school now. Whatever the case, you're confronting the reality that you have more applications to do, and limited time.
Unfortunately, this happens every year. Students apply, realistically or not, and now must face the brutal reality that there are too few seats and too many applicants. That said, I think it makes sense to get organized for this final push.
First, this is going to be a tough couple of weeks. There is no way around that. So face it now. Face it honestly. Expect to work A LOT. This is not going to be relaxing holiday break. Things didn't go as you'd hoped, but that doesn't mean they won't.
Second, get a plan. Figure out what other schools you want to apply to. That may mean applying to more "safe" schools, or it might mean applying to more "reach" schools (if you've gained admission at a school you like).
Third, you probably should reach out to some different people and see their reflections and thoughts on your application. Talk to a different teacher. Perhaps a family friend who works in education. You may have done everything "right." The statistics of admissions are just brutal. But if you didn't, you want to find out now and course correct immediately. It's not too late.
Fourth, set up a timeline. You need to be disciplined and focused if you want to finish. Set realistic goals. But know that there is no way you're going to be able to apply to five schools on Dec 31.
Fifth, take a deep breath. You'll figure this out. And even if things don't work as you'd hope, there are always other options. You could take a gap year. You could transfer after a year or two. Take a breadth. You're going to figure this out, and you're going to be fine!