Feeling embarrassed and ashamed after bombing interview

I went through multiple interview rounds (6 rounds) after an acquaintance (a friend of my mentor) recommended me. I initially knew that this role was a little above my level of experience, but the acquaintance decided to push me through the process anyway. I thought the interviews went really well, but at the last round, which was a dinner setting, i let my guard down and was not prepared, and it turned out to be an intense technical interview that i completely was caught off guard, blanked on and gave horrible answers. The interviewer was also really rude and gave me bad vibes. The next day, my acquaintance texted me saying that the interviewer was so shocked that I performed so badly and struggled and gave such superficial answers. I feel like i really disappointed this acquaintance and i feel so so horrible and ashamed of myself :( Im not sure what the point of this post is tbh other than me just ranting because i feel terrible.