What - new girl used to get bullied but I dont like her?

There is this new girl at my school, she’s been there for about 2 weeks. There are 3 girls at my school who don’t really like her and the girl knows and today the girl sat next to me and my best friend and was joking around (being quite a nice person) and was saying things like “we get on really well together” and “your funny, nice and laugh a lot gimme five your amazing!” Then the 3 girls said something and the girl said “You know what I used to get bullied so just leave me alone, this is exactly what happened at my old school” She wants to hang around with us all the time, at the moment she’s by herself. I don’t want to hang around with her because she can get really annoying, people keep saying things and me and my friends kept fighting and now we’ve got everything sorted and aren’t fighting anymore, maybe she will change things and we know each other as if we were sisters and we don’t know barely anything about her. But the thing is, she was bullied and she hangs round by herself and I know how she feels when you have no one and she thinks that no one likes her. What should I do?