He slapped her?.... is that ok? will he to me?

jessica

So my boyfriend told me that his ex babymama when they were together got into a bad argument. At the time he had a broken arm. So she began to hit him going strsight for his injured arm. He slapped her he said to protect his arm. I. feel bothered by that. I know its his past but does that mean he could do that to me? Should I be alarmed? In my past I had an abusive boyfriend Im worried.