My neighbours cause me bad anxiety.

A few days ago a dude who lives upstairs mistook my door from his own and tried to get it open, trying to use his key on my door and pouding on the door while yelling the n-word. I'm not even black. It went to him trying to break in basically and I had to open the door and tell him that he was at the wrong door. I was holding the metal pole as I opened the door, and at first he just said that he did live in my apartment, before I told him that no, this is my home. Once he went away, since then I've had really bad anxiety that he might try to get into my apartment again some day. He was clearly on drugs, which makes me even more afraid. I sent an email to the company that owns these apartments if they can put a safety chain on my door or if I can put one on my door by myself. I hate it, but I feel unsafe in my home. I know better than to call the cops on drug users.

Today I was on my balcony and I heard some woman from that apartment upstairs offering drugs to the people on the ground level so that just confirms my thought that he was a drug user.

Anyway, I just wanna know how I could feel less anxiety in this situation.