Am I the bully?

Question

There is a girl that I barley know who goes to my school and around 2 months ago we got into a stupid argument about a Facebook comment she posted on my picture. 
2 months went by and we never spoke (considering we never spoke before the argument this was normal) she sends me messages about how I'm a bully and how she is going to kill herself because of me. 
We had an argument that lasted a day, and it was completely back and forth, she tries to make me feel awful ( and succeeds) by threatening to take her own life.

Answer

Doesn't matter in this case. I'm guessing you guys are young? Teens? You need to tell a parent or teacher or someone about her saying she's going to commit suicide. It's not your fault even if you were being mean, but that's not relevant right now. Please tell someone she's saying these things

Answer

What did you say to her? All you can do now is apologize

Answer

First off, avoid engaging with drama queens. Just ignore them altogether- you never should have 'went back and forth'. 
Second, people who THREATEN suicide, rarely do it. If someone is going to kill themselves, they just usually end up dead.
(This sounds cold and unfeeling and I don't mean it to but I was trying to remain factual)

Am I the bully?

Let's Glow!

The Top Baby Tracker App: Embrace New Beginnings with Tender Care

The Top Fertility Tracker App: Your Path to Achieving Pregnancy

The Top Pregnancy App: Nurturing Your Journey to Motherhood

The Top Period Tracker for Empowering Your Menstrual Health Journey