The part where I was traumatized

So last week The Boy, Turtle and I went to library. It was supposed to be a fairly innocuous visit - I needed new books, The Boy likes to go to the library (mostly to go up and down the stairs because the library is on the second floor) and there's a small playground attached that we could visit afterward.

After getting my books I told The Boy he could play for a SHORT time. We had more errands to run, like going to Publix, but we had survived a decently long visit to Target already and I figured he deserved a break (and I deserved a medal - did I mention this was my first day on my own with two kids after Hubby went back to work?) There were a couple other kids playing already and he joined in (tentatively) and I let him play for about 20 minutes. That would be 20 minutes of me sitting with a weird old man who had brought his grandkids to play and wanted to talk to me about how it brings the older one (age 4) on his scooter (moped) but that he's worried about bringing the younger one (age about 6 months) on the scooter too (SERIOUSLY??) so they usually walk. And 20 minutes of me sitting with a mom that I would have liked to bond with but she was busy reading her self-help book and not interested in talking (although to be fair, she was probably trying to avoid the weird old man). AND I was trying to fend off the 4-year old (grand kid of weird old man) who was far too interested in Turtle and kept coming over to touch and kiss (!!!!) my 3-week old. And I couldn't figure out how to dissuade him.

After 20 minutes, I had my fill and tried to get Boy off the playground when he decided to through a fit while I held Turtle and broke from my grasp to RUN ACROSS THE PARKING LOT. In traffic. A very busy parking lot.

After I caught him, there was a lot of crying (me) and screaming (me) and hysterical insisting that he could have been killed or at least had to go to the doctor (hates the doctor) and no we weren't going to Publix (a travesty to him) and we were going home for TIME OUT. At home there was more crying (both of us) and some screaming from his bed (I'm not dead, Momma! I'm Not Dead!)

It was traumatic for me, and I attempted to make it traumatic for him (didn't really work) but what did sink in was No Publix. So he told Daddy when he got home that he Almost Got Hit By A Car (which isn't exactly true; luckily there were no moving cars very close to where he ran, but who am I to argue if it will keep him from running again).

What would you do? I'm not a fan of leashes (although after my brother disappeared in Montgomery Ward when he was three to go look at the vacuum cleaners, I do understand the inclination) but I can't go through that again. Next time we could not be so lucky, you know?

Question part two: How do you keep strange kids from kissing your newborn when their caretaker evidently doesn't see a problem with it?