I'm going to tell you about my positive experience, then, just to reassure you that there are lovely, thoughtful mummies out there.
I rather stupidly took my DD plus family to Wisley garden centre when she was just under a week old and I ought to have been in bed, being waited on hand and foot by all my doting relatives (yeah, right!!).
I waited while DH and DS were doing something or other elsewhere in the Gardens with MIL. The sun was pretty hot and I suddenly knew that, if I stood much longer, I was going to collapse. The only bench in sight had mummies and buggies surrounding it. "Oh God," I thought, "I can't handle an argument about moving buggies now!"
However, I grasped nerve and courage and asked the nearest if she could move her buggy so I could sit down. She looked at me, looked in the pram at DD, told me I looked awful and they all moved buggies, fussed over me, ran and got a glass of water for me, stayed until DH turned up and then told him off royally for daring to leaving me "in that state. She's just given birth to your baby!".
So, nice mummies do exist. I'm so sorry you had to experience the worst today.