Jordy, I'm sorry you're having such a bad day today, and I understand your frustration. It can be very hard when you just want to eat the same food everybody else does. What worked for me was realizing that with this diet I'm finding all kinds of good things I wouldn't have tasted before. Like I was at Whole Foods yesterday and I came across these Lundberg rice cakes in tamari sesame flavor. They're so good that I could just eat them dry! So yeah, I still have days when I'm down and just want to eat whatever (like those cookies before) but fortunately I also have days when I like all these new foods.
I think the reason doctors won't tell us what to eat is because (at least here) they're very test-result oriented. Which makes sense because that's what they went to school for. They won't tell us to give up dairy if we tested negative for lactose intolerance. So while I'm glad that I had testing done and know that there's nothing terribly wrong with me, I also realized that I am the only person who can help me. So I'm searching for answers on the internet, books, other people's ideas (such as this board) and I'm playing my own guinea pig. Sometimes it works and sometimes I get sick.
It seems to me like you're trying to be too hard on yourself and it's not working. Don't beat yourself up over one cup of coffee. Maybe you'll find out that you can actually tolerate it once in a while and that way you don't have to give up your favorite treat forever! I truly believe that I'll be able to enjoy at least some dairy ocasionally one day once I get a bit more stable. I think we should do what feels best of us. And if you think this diet has taken an emotional toll on you maybe you should just try to give it a break for a couple of days and see. At least if you feel a lot worse you'll know what to do to get back on track.