Jealous

Hi I have a problem about my jealousy towards my fiance and it's causing me to have that push-pull feeling in our relationship. He had a history of cheating on me, he met this girl on facebook and I already was having suspicions about her but he just kept telling me she was his friend, then later I find out that he hung out with her with his best friend and they ended up making out. I was tremendously heart broken and sad, when I confronted him about this he caved in and cried when I told him I know the whole truth...but in spite all of these things I still accepted him. This was 3 years ago... I forgave him but I can't seem to forget it. Now he plays on xbox and there's nothing there but his women friends, I told him yesterday that it bothers me and I don't believe that this is some sort of experiment his doing. I told him "You are always giving me that excuse and I don't believe that anymore. Why can't you just tell me that you are friends with them?" and he said "most of them are sluts and I don't care about them." I replied, "YES you do care about them because if you didn't you wouldn't even care of replying to their personal messages or voice messages on xbox." He didn't say anything to that... Even though I said I was okay with him having friends online because I'd rather have him talk to people than becoming a recluse, I still feel fearful that history might repeat itself. Today I am trying to give a little bit of time for myself and think about the whole situation. I might just be over analyzing it but I can't help but get anxious sometimes. Now I am scared that he might be talking to them on his cellphone (he never gave me any reason though) I am just so paranoid now that it's eating me alive. It came to the point where I want to hack into his cellphone usage (but I didn't do it)... I am honestly going crazy... Am I that jealous? I never was like this, I was okay with my exes talking to their exes even, or them hanging out with their girl friends. I don't know what is happening to me...please help. I just kept telling myself that I hang out with mostly guys (but I never date them, the moment I find out they have feelings for me...I leave them in the dust and never talk to them again) and I shouldn't put too much thought into it, I don't want to create a double standard. But why am I jealous? I want to know why I can't seem to be okay with him, I don't want to be one of those psycho women who keeps on finding flaws from their partners even if there is nothing to worry about.

Move on...:)