at the train stop

I was on my way home from a rehearsal on Saturday evening. I wasn’t having a particularly bad day but it wasn’t great either. I don’t know why, but I just became overwhelmed with feelings and all the shit that’s been going on lately. I hate it when this happens. I’ll be completely fine one second and then the next I’m bawling my eyes out or I’m so angry that I start hitting things or myself. i don’t understand why this happens. it’s scary because I was literally standing on the platform at the train station waiting for the train to come so I could jump. I called my “boyfriend” (we’re not officially together for various reasons) and he didn’t answer so I got more anxious cause he usually calms me down. I didn’t know what to do so I ran down the stairs to the lower level of the station and just curled up and screamed to myself. I imagine I was quite the sight to all the people there. Anyways, my point is, I just want to know why this happens. I just want to understand. I was a perfectly normal 17 yr old girl 8 months prior to all this. Well, not entirely normal but normal for me. I want to at least know how I can control these feelings so I don’t make a spectacle out of myself like that. It’s one thing for me to freak myself out but I don’t want to have other people getting into my business. Please help. I have my plans on how I want to off myself set up already, I just want to live and be as happy as I can and make everyone else as happy as I can make them until then.