Jealousy

I've always had jealousy issues. Since we have been here in OKlahoma I always told my husband he had better not talk to any females at work about anything other then work related issues. He told me for the past year now that he does not talk to girls, that no girls even work in his unit. So yesterday some girl tries to add him on facebook. I ask him who she is, he says he doesn't know. So I sent her a message asking her who she was. She writes back saying "are you serious? It's me. How was your weekend? Mine was good.I'll see you at work Tuesday. Bye. Her name was Jessica. So I showed Mike the message and he was like Oh I know her. I said to him I thought you don't talk to girls at work. He then starts saying he does and he had to lie to me so he didn't have to hear my mouth. I was soo pissed off!! I still am and I honestly feel like he cheated on me. My definition of cheating as always been different from everyone elses. To me cheating is anything that involved another female other then family. So if your married and are talking to another female your cheating. It's crazy I know but thats what I believe. I can't help it and I can't seem to stop. I refuse to talk to him right now because of this. Every time I think of him going to work Tuesday and talking to her it makes me more mad. Anyways....I'm going now to try and not think of it.