I've held off weighing in on your thread because I don't know much about cross dressing. My wife is M2F and will be starting hormones in the not too distant future.
I think everyone else has given you good advice. I'm not going to add too much other than if you do go the therapy route, please try to find a gender experienced therapist. It will make a significant difference as they will understand gender issues such as cross dressing and transition.
One of the things I said to Dani after she came out to me was "Is this all we're going to talk about?" It wasn't that I didn't want to, but I was getting sensory overload. She had 30+ years to figure this out, I was working on a month or so at that point

We as SO's often need a lot of time to adjust and accept things. Often our partners want to go full speed ahead because they now feel free having gotten the monkey off their chest. It sounds like your partner's gone to light speed; he needs to slow down and let you catch up.
Unfortunately, we can't tell you exactly what your partner means by what he says. We can make some educated guesses, but he is the only person who can say exactly what he means. Sadly, if you must wait until he returns from duty, then there isn't much else we can suggest other than talk to him then. But writing down what your concerns are is a good idea. That way you can vent some anger and you also won't forget anything.
*However* you do NOT have to do ANYTHING you are not comfortable with and that includes going out in public with him dressed. If your partner is not accepting of that, or accepting of the fact that you want some more specific answers and time to make your peace with things, then I'd really reconsider the whole proposal/marriage. Secrets are not a way to begin a relationship.
If you do decide to continue the relationship, then I'd like to recommend couple's therapy sessions. Dani and I have found them very helpful for our journey through her transition.
Sending lots of hugs,
WR