I feel your shame. I stand in solidarity with you.
My 30th was similar, though I was actually genuinely upset for valid reason (even if I overreacted).
I had spent alot of money on a nice hall (it was alot of money to me, anyway). I had the catering all planned out. Again, I was spending a decent amount of money on a very decent buffet. My mother, however, decided that she was going to jump in and take over with the catering because "you are spending far too much money on that, you don't need that amount of food, I can get it cheaper, etc etc". I reluctantly let her take that on, making it clear that there was going to be 150 people there and to please make sure there was enough food.
A couple of days before the party, she showed me this hideous plastic light up candle that plays a tacky tune and said she was bringing it. I (very politely) asked her not to, as my best friend was making a lovely themed cake and I didn't want a large plastic candle thing stuck on the middle of it.
Cut to the chase, there was barely any food (that's not an exaggeration - there were 2 plates of sandwich triangles, a bowl of sausages and sausage rolls and some crisps) and I was mortified, having told everyone that there was a full buffet.
Then I asked everyone for a nice group photo. Gathered everyone together, I was holding the cake, and my Mum kept trying to stick that f*ing plastic candle holder on the cake. I asked her to stop. She refused. I got very upset and started balling that she had ruined everything and why couldn't she just let me organise my own stuff, because, well, I'm a grown up and very capable of throwing parties.
Yes, I was drunk. But then she started loudly tellif me that I was ruining my own party cos I had drank too much, because I paid too much for the DJ, because the cake was terrible and I shouldn't have paid my friend to make it (even though it's her business and I wanted to support her), etc.
Yes, I sound like a spoilt cow. No, I don't care. Trouble with my mother is that she ALWAYS has to take control because in her eyes, I can't do anything right. What I WAS ashamed at was the way I felt with it in front of my friends. And I'm still feeling the shame.
So yeah, I lost it. This was 12 years ago and I'm still very bitter!