Refusing a minor's phone number when she asked, am I in the wrong?

I have started to distance myself from her and she'd notice and say things like why are you ignoring me. The reason is because she's 13 and I'm 18 and I don't really want to risk my future for that. She's a bit rude as well saying things like I'm pathetic and a weirdo. Today she asked for my number. I said I don't think it's appropriate for a 18 year old to have a 13 year old's number and she called me petty and weird and that she had 'many' guys older than me on her phone.

Am I the ******* for refusing her number and then her straight up insulting me for no reason? My friends say no but I feel bad refusing it because I haven't had to refuse numbers before. I just don't find it right at all if I were texting a minor which could get me in trouble and it's just weird hence why I refused.

Now the vibe's really weird because I'm ignoring her in my school and she doesn't talk to me anymore which is great but still am I in the wrong or is she? Should I stay away?