Yeah, I have heard that you shouldn't really believe anything that they're saying just because they're in such a bad place, of course there's going to be a lot of negative comments.
Unfortunately you can't believe the positive things either. My WAW said things to defuse the situation that were pure BS. Back before I knew about OM in my sitch, when I asked my W if she wanted to have sex with someone else, she looked me right in the eye, and without hestitating said "No, I can't even think about that." LIE. After being confronted about the OM, a few days later she said "We've decided to cool it and just be friends." LIE. That was over a year ago, and I still to this day can't believe she just lied to my face over and over. Once trust like that is shattered, rebuilding is VERY difficult, if not impossible.