wow devastated, that's a challenge. it sounds like you are at a personal breaking point and if that's the case, like rick always says, if you keep doing what you've been doing, you'll keep getting what you're getting and what you're getting isn't working it would seem, right? i think expecting full disclosure is a must, but then again, it's about what your spouse will do and if they won't, then at some level you're in a bit of a pinch. some spouses would then say, OK for me to heal, I need a lie detector so we're going to get one and then see what that says and if it works and proves you're telling me the truth, we can heal and enjoy lives forever. however, if it shows that you're not telling the truth, i will expect full disclosure of what you're hiding.
some spouses forgo the lie detector and will simply issue an ultimatum which says: if you don't tell me everything, i'm leaving. i know you think i'll leave once i hear everything, but i commit to not leave after you tell me all you need to tell me for at least three days. after three days, i can't guarantee it, but for the first set time, (for some it's 2 or 3) i won't leave. but if you don't tell me the truth, i'm leaving as i can't trust you or cope with this.
another option though, would be to consider getting help for your own recovery, and seeing if you can't better cope with it. some spouses are stuck in situations where they may never know the truth. they will ultimately have to either 1. decide they know enough and get healing and recovery to move on in the marriage and realize it's over, they don't know and they won't know. 2. decide that they can't keep doing this and living with this pain and hurt, so they ultimately decide to separate and ultimately divorce for their own healing and recovery. you never want to make a rash decision so i certainly encourage you to think hard about the course of action you take. does this make sense? i'm happy to continue to dialogue with you more if you like. hope that helps in some way.

Devastated.....i get it, however, the problem is, you have only a couple choices. you can keep doing what your doing and get help to cope with the pain of it, and then start a new. meaning build a new marriage, with new openness, and with a new approach, and get the best type of professional help you can and 'see' if you can move forward in recovery, though you have no proof she did or did not have an affair. the reality is though, you can't change history or the past and if she did, you will have a good sense of relief at finally knowing the truth. if she did not, you can then put things in proper perspective and move forward.
OR, you simply can't handle it and need space to heal, and grieve, and consider what you ultimately want to do. depending on what state you live in, maybe it's time to at the very least, separate. some states will or won't allow a separation so before you do so, I'd make sure you know you're legal rights or else it could cause some difficulty for you in the divorce. perhaps getting some time to breathe and think through this all will help you? I don't disagree with you, meaning, what kind of marriage will that be and how can you ever trust her again.....but is it enough of an issue to cause you to divorce and move on? would she take the lie detector?
i would consider talking to her and saying 'listen, i love you, i want you, i want to be with you and i want to have a happy home (just giving ideas) but I need you to know, that I need the truth. I need to know it all if I'm going to live securely in our marriage. so if you don't tell me the truth, i feel like I need to separate from you and heal. i feel like if i don't have the truth, i'm living a lie and if you can't tell me, i need to leave and if she is not willing to tell you the truth under those circumstances, then you'll probably need to follow through with the threat. just some more thoughts for you.