I understand your situation and sympathize. But you have to understand that you are already creating problems by labelling this person as a "gossiper". Perhaps you have good reasons for believing that she is (like, perhaps, she gossips all the time), but entering into this situation with this pre-judgment in mind is going to affect how you treat this person, and it will show. And that will only make matters worse.

When you're stuck dealing with people you don't want to be around, sometimes all you can be as positive as possible. I mean, this person may be immature, but you don't know everything about her, right? Perhaps she is like this for reasons you don't know about. It's surprising what secrets people have - things going on or that have gone on in their lives - that explain why they act out.

So maybe try to keep a positive attitude and find common ground. Perhaps you or she will bring up a movie/tv show/band that you both like, and you can bond that way. It doesn't mean you have to be friends, it just means that you can cope with the situation.

Good luck