How to help a friend?

this friend, jess, causes drama, and overeacts about everything. I no that i realli can't hang out with her outside of school because it brings me and my other friends down, having to deal with all this drama. Anyways i wanna no how to like still be friendly with her. but also tell her that we realli can't hang out outside of school? but i don't want her to get too mad, cause she realli has no other friends? How should i tell her??