How do you deal with jealousy in a relationship?

One of the biggest personal problems I’ve have is jealousy. Whenever I see my SO with the opposite sex, I feel scared and angry, because I’m afraid of my SO leaving me. It’s not the greatest feeling, and I know it’s wrong, as if my SO would leave me that easily, then the person isn’t worth my time. Just having the feeling is bad, how I currently deal with it is worse.

I lash out at the person, either very passive aggressively or aggressively. I’ve also talked to my SO about it, but it seems that I’ve talked about every person of the opposite sex related to her. Just telling her my feelings about it, and sometimes when there are no words exchanged, its just the body language and actions that I do. Other times, I attempt to make my SO feel jealous by initiating or engaging in interactions with the opposite sex, though nothing too serious. Not the most intelligent or mature thing to do. My SO responded to this, after a duration of time, by pointing out that SO feels like I’m isolating SO’s social life.

I’m in need new ways of coping with jealousy, before I ruin this. This may seem like a huge red flag on her part, but I’ve been in past relationships that the other end didn’t have the greatest commitment, this is just a defense mechanism, from my perspective. Also, my supreme immaturity. Thanks.