Rejected from Cambridge PhD despite strong supervisor support :(

I'm sorry to any of the readers who this post might induce anxiety in. Context : In September I reached out to a PI at Cambridge for PhD prospects and we had a meeting, during which I was asked to draft a research proposal as our research interests aligned very closely. PI reviewed the proposal and was VERY supportive of it and asked me to apply without any changes. They also mentioned I that I should note in my application that they support the proposal fully. Suggested me to apply for eligible funding and remained in touch. I applied before their December deadline after which was complete silence. No replies from the PI to any emails. My anxiety got the better of me with no response at the 3rd week of January , I emailed the PI and got no reply. I finally reached out to their office asking for a gentle update, during which a secretary went through the files and informed me that I was not shortlisted. That's it. This was my strongest application among all the ones I've made, strongest fit to the group and strongest supervisor support.

I have no hope anymore even for any of the other applications. Being shot down by such an unpredictable, opaque and unfair system has really affected me so much. I feel like I've aged by years by this process , developed an anxiety disorder and severe self doubt issues.

If anyone has been in my situation and gotten out if it with success (of whatever kind) or gotten bigger/better opportunities by not giving up... I'd really like to hear it as it might save me.

Thank you ❤️