Why are people so mean?

It seems that I can't even go out of my house anymore for a quick trip to the gas station without running into at least one mean, rude person. Is this just the area in which I live?

I origionally am from a small, do nothing town, and was forced to move to Washington D.C. since my husband joined the military. I have never had problems making friends ever in my life until I came here, and I don't know if it is just society in general is just getting crueler and crueler, or it's the area I live, or if it's just me!

Sad enough, I don't even desire to leave my home anymore because of who I am going to run into that is going to ruin my day. I don't know how to handle this, except for buying some relaxation medication and just taking it.

This is just one example:
Yesterday I made my quick trip to the gas station to pick up some cooking spray to do my christmas cooking and this lady in line beside me started talking to my little girl. I smiled. And then my daughter said, "mom, I'm hungry!" she only said this because she wanted junk food as I had just fed her a big lunch, which you could still see all over her face! and that lady told my daughter, "awe! she's gonna take you home right now and feed you!" (what nerve!) I said no, I'm not!, and then the lady said, "Oh yes she is baby! she's gonna take you home right now and feed you!" I said no! no I'm not! and so at that point my little girl started balling and throwing a fit just cuz this lady couldn't shut her mouth where it wasn't her place to say anything anyway!

What is wrong with people? What could I have done differently? I could really use some advice. I am trying to live a christian life, to love people, but how can you love people when they are this way? If anyone knows the secret, by all means please post a comment and let me know! Thanks to everyone.