Should I stay at a job that makes me absolutely miserable?

I have been at my job for three years now and it has gotten to the point where I am just miserable. I like the job it's just some of the people I work with. I am in my twenties and some of the older ladies are hateful to me. They always belittle me and cut me down. Sometimes they do not even respond when I speak to them. They make me feel like I am not a person and I do not count. There is a lot of backstabbing going on. They talk about everyone, I would be naive to think they don't talk about me either. They are always griping and complaining- it is just a hostile environment. In the past I have always gotten excellent reviews from my supervisor and have gotten raises but this year they have been saying a lot of things about me to him. He will hardly speak to me now and gives me mean looks. I am a quiet person and a hard worker. I go in and say hi to people, don't cause any trouble and just do my job. The only thing I can think of is that I have a bachelors degree and they only have an ociates, therefore I make more money even though I am fresh out of school and maybe they are resentful of this. It has gotten to the point where I cry at work a lot because they hurt my feelings so bad. I feel embarred for doing this and I know it just fuels them by letting them know that they can get to me like that. I could look for a new job, but I don't think that is the solution since I will most likely encounter people just like them wherever I go. Everyone tells me to kill them with kindness but it's hard when they're killing me with meaness. Should I keep trying to be nice or should I just stop speaking to them altogether?