Rumors about me being spread

I’m 21 and currently in college. Last night I found out that this 18 year old girl that I have never met is spreading horrible lies about my boyfriend (23) and I. She’s saying that we constantly fight about her and she told his group of friends that she intends to break us up. She also apparently claims to know me when I don’t even know who she is? I don’t feel threatened because my I trust my boyfriend, but I’m just irritated that this girl is acting like a child. A lot of people apparently don’t like her because she likes to lie about everything even though it’s obvious. You’re in college now, stop acting like you’re still in middle school. Jeez.

Edit: my boyfriend told me what she looks like (piercings, hair dye color, ethnicity, etc.) idk who she is. I forgot to add that she told his group of friends that she’s interested in my boyfriend and wants to get with him. They told him everything she said and they told him to tell me because of the rumors that she has been spreading.