Well, things aren't sounding so good are they?? Since you are the same age as my eldest dd, and a few years short of my ds, I will tell you what I would tell them.
1. Decide how you would like to see this story end...best case scenario.
2. Go on your trip and give this a ton of thought.
3. When you get home, make a 'date' with the dw to discuss options.
4. Keep that little boy in mind....he is hurting enough. Try to take the path that will hurt him the least.
5. If a 'parting of the ways' is the best path...so be it. Better off alone than with the wrong person.
When you sit with your dw and discuss your options, you will need to be brutally honest. She should be also. Only honesty is going to get these issues resolved. Counseling is a wonderful thing...it will help you decide whether or not the marriage should, or shouldn't, continue.
If you both love each other, as you say you do, then anything is possible. The one thing that I keep seeing is a lot of immaturity and unrealistic ideals.
I take solo trips to WDW...my dh has told me to go, in fact has suggested that I go for longer than 4 days. I believe him when he says to go, have a good time. That is maturity at work. How can you have trust in what someone says if they change what they are saying at every turn?? You can't. I would imagine that your dw has some issues from her first marriage/relationship. It is so hard to get past these issues sometimes that we inadvertantly take 'stuff' out on others, even if we are trying to do better. You need to decide if it is worth the 'hard work' to keep your marriage together.
Do you think that if you canceled this trip to WDW and told your dw that you had canceled it in order to get your marriage back on track it would make any difference? Since I don't know either one of you, I can't say...that's for you to decide.
Should you have posted her email for all to see? Well....maybe not, but I know how it feels to need to vent and to have people be on your side. I sure as *&&^ wouldn't let your dw know that you had posted it...in fact, I think I might go back and delete that part of your post, just to be on the safe side.
I think you both need a bit of growing up. Now, off to decide what it is you want out of life and this marriage...go on with you now....think, boy, think. And no children from this marriage until you get it all worked out!!!!