He is to jealous? Is this likely to stop?

I work in a mental health unit as a co worker helping male clients. A year and a half ago when I first started I was asked to help a 28 year old male client for six months, he was very withdrawn and depressed when I first started, but after a month of me helping him he became more happy and sociable with other clients. I then started to notice him getting very jealous when ever I was around other male staff and clients and it got to the point where he would watch my every move and get very angry! He then got violent towards me. I was moved downstaires a year ago and he still reamins to be very jealous when im ouside having a break with male co workers and gets angry and he sulk. Its like when he hears my voice he looks depressed and looks down and when im talking to other people and it makes me feel very guilty. Please can you help me understand this please and have some advice? Im a 24 year old female and I havent had much lifes experience in this kind of thing.