I am worried about this and need advice?

Hi. I would be grateful of any advice anyone can give me. I am having a few problems at work. This is something that has been going on for several months. I work with mentally ill clients and have done for many years. Recently we got a new admission and this clients son is causing me some distress. This man has made allegations about me breaching confidentiality about his parent which is untrue and the evidence has been produced to show that. There is no case to answer there and this man knows it. However, since then this man has been intimidating me at work, towering over me, glaring at me and generally making me feel ill at ease. He has for a few weeks now began calling me very derogotory remarks about me to my work colleagues who have all put witness statements in to the management in my defence. These remarks are hurtful and they have worn me down. I asked my manager to speak to him and she said she would when sufficient evidence. There must be 30 witness statements put in place now and nothing has been done. This man is 6ft 5 and has a voilent temper and has put women in hospital so I am a little concerned for my personal safety. I am a single parent and I am fearful he would follow me home.I have been off work on leave for two weeks now and due back at work this week and I do not want to go. The idea of going back into that place feels me with dread and I am not sleeping or eating properly. I seem to have a permanent knott in my stomach that wont go away. I am seeing my GP on wednesday for a sick note, but at the same time am annoyed that I am going to be losing money and being manipulated by this man for no reason. I have been in touch with my company today and they have told me nothing has been done. I feel thay are not taking me seriously but I am worried that my own mental health is at risk. Has anyone any advice, as I wonder if I am to involved in the situation to think about it rationally. I have been told that I can ask for the man to not be allowed in the workplace while I am on shift, although I feel that would affect his parent who looks forward to his daily visits.Many thanks