How can I find out?

Me and my wife have been married for almost 2 yrs I love her very much but I am always worring that she is going to leave me or she is searching for someone else. She is very secretive on the computer puts on 2 passwords to log on to windows deletes all sent messages except to compaines or certain family members on our home computer she gave me a guest account. She always clears history now she got a laptop and gave me the home computer but before she did she rebooted the computer now she takes her laptop with her and puts in on the floor besides her when she sleeps she also hid it under the bed in a way so that the bed would have to be lifted up to get it out. She stays late after work almost everynight and doesnt feel she should have to tell me where she is going and when she will return. Recently I found out she was taking birth controll pills behind my back am I just going crazy or should I be concerned how can i find out if she has secret accounts or other email accounts .