I wonder if he took what he told you about the A's back to avoid getting in trouble.
I think that its interesting what you said about his hopes and dreams. He cant realize anything if he just gives up when things get hard. Absolutely nothing is easy all the time.
You don't have to let him go, as such, but you do have to let him go down this road on his own. And yes, it is excruciating. This is your marriage too. What happens to it isn't all up to him.
Always remember that no matter what: You have a bright future, with or without him. The things that we talk about here, 180's, GALing are all things that will help you to heal yourself, and really make you a more well rounded person. I learned to ride a motorcycle, started volunteering for 2 different orgs. went flightseeing, camped, took on a new research project, and looked around on here for situations to chime in on. It kept me busy, and the experiences were really good for me.
And... Not to offend anybody... I dont believe that is right for anybody on here to make a judgment about what you should do based on the length of your marriage. We are all here for the same reasons. The length of a M cant determine the depth of someones commitment. Its just not that simple.
I guess I gave the wrong finger to the wrong man...