Unhealthy relationship

Hi girls, I will ask your for advice and help. I am so obsessive with my boyfriend, we have been together for a year and a half and I am extremely jealous. I can't even stand him saying hi to a girl, pr telling me something about another woman. I know i have to change but i just do not know how to do it. I even feel sick because of the constant anger. I don't to be so insane, please tell me how to deal with that.