Coworker continues to suggest colleague will get fired despite having no basis for that comment: 'The first time she said it tears came to my eyes and I guess that's why she's continued to say it'

Nobody deserves to be singled out in the workplace, unless it's for good. Especially by your coworker. It's one thing to not be friends with a coworker. After all, you didn't exactly choose each other. It's an entirely different thing to feel like you coworker doesn't respect you. That can be helped. There is never any reason to disrespect anyone at work, especially if they haven't done anything to you. There is always a professional, courteous way around the situation if you're willing to give it a shot. It's never right to make someone feel like they don't belong, especially in the workplace. Everyone has different backgrounds and brings something different to the table. This should be valued and understood, not dismissed and made fun of. Creating a hostile work environment is never the way. That bad karma will come right back to you and you'll regret everything. 

But what do you do when a coworker makes you feel like you don't belong? How do you respond? It's not like in a regular situation where you can just avoid them. Chances are, you have to show up every day and try to make nice. But that can take a real toll on your mental health. You want to stand up for yourself, but that's not always easy to do. You want to assert your boundaries and let your voice be heard, but there is some risk involved in that when you're trying to make a good impression among your colleagues.