Lost ..........what to do? URGENT suggestions wanted please?

My husband is scheduled to go on a fortnight long business trip tomorrow. Upon checking his mobile , I came to know he has forwarded his entire itinerary to another female colleague *** good friend of his (over whom we have already a huge difference of opinion since I caught some intimate sms to & fro ) . I donot understand what is the need of my husband to update this friend of his minute by minute schedule when he never bothers to include me so much in his office life. No way is she connected officially to him to warrant such a flow of information as she is in another department all together. Also since I confronted him couple of years back , he ured me that there's nothing more between them other than friendship and hasnt even mentioned her in ping since then, But he keeps his mobile locked all the time. I also do not understand why he needs to pword protect his mobile , I dont do so with mine. HISTORY - he had an affair 8 yrs back when I was pregnant. I had discovered that also through his voice mails. We had a rough time but stuck it out because he is committed to our child and im committed to both us and our child. Whenever I confront him with anything untoward his favorite tacit is to remain quiet and go about the day as normally as he would have OR to go on the offensive with me about checking up on him. Not that I regularly spy on him but from time to time I get "edgy" and to my misfortune have always hit pay dirt (twice in 8 yrs since his cheating on me ) . No , I cant divorce him and warning him or being upset about it hardly is getting him to change his ways. All he does is become even more careful and sly but continues having the intimacy with his female colleague which disturbs me. He has even told me he finds her ugly looking but because of his own past behavior and the sms I caught , I find it hard to trust him or that its only friendship. Friends do not get into so much details n so many calls through out the day. I was letting "sleeping dogs lie" for my child's sake but this latest "finding" makes me wonder if he will ever change. Neither will he leave me nor will he leave his ways. Im left with all household and child rearing responsibilities while he has his "side-kick " in office and a picture perfect home life. I feel used and like killing myself. Please help with serious suggestions do not and please do not mock or preach me. Should I let him know "I know" before his departure tomorrow (which will only prompt him to change his pword ) or just let him go and after he comes back keep checking his mobile to c if he is really involved with her ? If I confront him he will say it was some interdepartmental communication or some bullshit Last time he had actually got her to say she sent those sms by mistake to him when actually she was sending it to another person by same name !!. I just want to bid him bye tomorrow without even bothering to take the details to his hotel etc , not call him up even once while he is abroad and splurge a lot on shopping . And continue on the same note even when he is back .Lets c how he feels about being used . What say ?