back flashes I guess.

Gr
I know this isn't as bad as it could have been, but In middle school I couldn't walk down the hallway without guys making comments on my butt like " I've been all up in that ass", or "that ass is mine" Some would try and grab it but I blew it off. This one guy took it to the extreme writing me explicit notes of his rape fantasies of me. Touching my thighs in class trying to get me alone. One day it hapened. He followed me to the stairs on my way to the gym. He pinned me to the wall and groped me. Someone walked in on it. (Another guy) so he stopped. This guy then saw that it was okay he kept grabbing my boobs when no one was looking. I never said anything about the other guy or that they physically touched me, but one day the teacher found me crying and so I showed her all the notes and she took them to the office. I had to write everything that happened down but I didn't have the nerve too. Only what he wrote never what he did. I know I should be greatful nothing else happened, but now 3 years later it's still affecting me. 
Anyway long story short. My best friend told me that our old boss raped her. Well he showed up at work yesterday and proceeded to try and get me to come work for his company then he gave me his number and kept trying to get me to hang out with him and such. I wear an Apple Watch and it keeps track of my heart rate, well I went into a panic attack while he was flirting with me and it called 911 in the middle of work. Anyway I ran to the bathroom to calm down and tell 911 that I was okay. I couldn't breath after tho. I just kept flashing back to middle school where I was too afraid to move. I was up until 5 in the Morning unable to calm down. He again showed up today and I ran to the bathroom when he tried to talk to me. How can I make seeing him not make me go crazy? 
Update: I just had a nightmare about it