I know how you feel :/ I've had a lady tell me off for taking my dog away from her dog. I was so annoyed because it was my old dog (she was about 10 at the time) and I only took her down there because no one was there. She HATED other dogs and was old and scared and wobbly so when another lady showed up with her dog I just smiled and picked up my dog and started walking away when she was all "Let it stay and play ra raa raa" It was weird and she made me feel bad.
I can understand the lady's reaction but I'm sure she would have understood if you had explained why you left. I get very disappointed when I take Taz to the off-leash park and people try to keep their dog away from us when it is clear that their dog is happy/accepting/apathetic to the presence of Taz. I feel like yelling "I'M JUST TRYING TO LET MY DOG SOCIALISE!!!!!!"
People treat their dogs like mini-humans that they need to protect, when unless a dog is aggressive and completely unsocialised, the dogs can sort it out for themselves. They learn when to sense they aren't welcome and move on most of the time.