Abusive Friendship?

Hi, I'm Plum and I believe my friendship with my friend of many years may be abusive but first hear me out until you tell me I'm over-reacting and over-dramatic.

How it All Started:

I meet Em (fake name) in fourth grade we started talking 'cause we had found out we both had the same birthday and same interests, that was the day we would become beat friends. At first our friendship was amazing, Em was kind and caring and we were always there for each other and graduated Elementary school the bestest of friends but when we started middle school everything would change.

Seventh Grade;

At first the change was small it would just be an occasional "Shut up,K!" but what started as just a "Shut up,K!" turned into a push into the desk and kicking my chair away from them as we sat by each other in math class. I didn't like it but I feared if I stood up for myself then I would lost Em so I kept quiet and passed it off as a thing friends always do and say to each other.

Deep down I knew that wasn't true but I forced myself to believe it.

The Summer Between Seventh and Eighth:

I went through depression again and at first Em was there for me but when I went into a panic attack after being told by a classmate in my summer school class to die (The exact words were much harsher) I went to Em for help and at first they were helpful before they told me that basically they couldn't do it anymore and left me in a middle of a panic attack. Since that day I went through fighting depression by myself. I don't think or talk about this incident hardly at all ' cause it still hurts and I don't think I'll ever fully forgive them for that.

Eighth Grade:

It was basically the same thing; a shut up,a push, a kick, saying no one cares if I bring up a topic in a conversation with Em and our friends and all that. I laughed it off forcing myself to believe Em was just joking in a harsh way but deep down I wasn't the same as I used to be. Now when Em or generally anyone raises their hand or arm to quickly I'll cover myself in case they decided to hit me and I started growing afraid of talking to new people 'cause I feel if I say anything they'll tell me to shut up like Em has for quite a while. We left middle school still friends but not as close as we used to be.

Ninth Grade Aka Now:

We've just started nineth grade and they still treat me like this but now it went back to being just a "Shut up" and "No one cares" but two weeks before winter break when I was sitting by them waiting for school to start they stepped on my already injured knee and slowly kept applying pressure while I begged them to stop saying that it was already injured and this would hurt it more but all they said was "I'm barely pressing down on it!" what might be 'barely pressing down on it' for them may be full on pressing down for me. Why did Em do that you ask? Because I said something to another friend of ours. It took a week for my knee to heal.

Epilogue:

Em might be joining theatre soon and I'm terrified of them joining ' cause now the abuse will happen there in a place I oh so love and I fear that the others might join in with Em and I don't want that to happen from the people I care deeply about again.

A person can only take something for so long before they snap and I might just be on my breaking point.

Questions:

Do you believe this is an abusive friendship or am I being over-dramatic?

If you believe it is abusive, what can I do to stop it?