I'm going through something similar. My problem is I'm so fixated on the application that I haven't actually written anything since the beginning of this month, and I'm scared that my application play will be my best work. I don't know what to say except that it will pass. If I don't get into anywhere this year, I will keep writing. Finish my new play and try again. I'm not happy with my day job, so I'll also apply to other jobs.
Rejections are terrible, as I have applied to numerous developmental programs and received rejections from each one. My recommenders and old professors told me that's because 1) I wrote about sexual violence/abusive dynamics that are a little hard on the audience 2) I wrote plays with minority characters who are a bit hard to cast 3) I'm an international on a work visa, and most theaters don't know how to navigate the situation. As much as those reasons make sense, it sucks. Nothing people say can make it suck less. I can only remind myself that a lot of great playwrights also face rejections.
I hope this antidote will be helpful: Back when I was applying for jobs, I applied to 1200+ jobs (I stopped keeping count after #1200) and got 10 interviews, and none of them turned into a job offer. Mostly because companies are unwilling to sponsor visas (because of the policies of the current president). I kept trying and eventually found one. "Exhausting" is not enough to describe that journey, and I can't say my current position is my dream job, but it did work out.
P.S: I saw you only applied to four schools, and two schools haven't really posted their decisions. Hang in there.
P.P.S: My personal opinion is that Yale still hasn't released their semi-finalist list. So far, the schools that are a bit early compared to previous year timelines are UT Austin, Iowa, CMU. UT Austin and Iowa are in more conservative states; CMU has a rather conservative program (based on my interview experience), so I assume they want to secure their funding before the orange guy makes more unwelcome changes. However, schools in more liberal states (UCSD, Yale, Brown, NYU, Columbia, etc.) are adjusting their programs to fit the policy changes. That might mean we hear from them a bit later.