My husband is a crossdresser, what should I do?
This is a tough question to answer. A lot depends on you. Here are the actions you can take; decide which is best for you.
Many people think that a crossdresser chooses this behavior. In fact, it's rarely a choice; it is usually an emotional imperative.
Suppressing his opportunities to safely dress can lead to his finding ways to do it behind your back - often in unsafe ways. And once he starts having to sneak around to dress, the sneaking can, itself, become a thrill and expand into other areas like other women who will tolerate it, children, or experimenting with other men.
I know that sounds pretty scary, and I really don't want to scare you. There are research results that bear out my own personal knowledge.
I also don't want you to feel like you have to accept something you can't handle. On the other hand, both research and personal knowledge suggest that many women can, with professional help and exposure, learn to accept and even appreciate this "feminine side" in their husbands.
Marriage is, of necessity, a series of compromises. A fully developed relationship becomes an interdependence of the two people such that they are, in effect, a single entity. I was lucky enough to have achieved that state with my late wife. She had a fairly strong masculine side that balanced out my feminine side. As she became more comfortable with that our marriage grew stronger. I'm convinced that if she were still alive I would not be seeking gender reassignment.
So my first suggestion is that you try to have an open and civil conversation about his dressing and your feelings. If either of you gets uncomfortable with it, remember that it's okay to stop the conversation for a while. You may also find you need professional help with the dialog at first.
Don't expect that either of you can be fully open at first. After all, this is not something most women grow up expecting from their husbands. Certainly this is something that he's been hiding most of his life because everyone has told him it's "wrong."
Another thing to consider is that crossdresser often get an erotic thrill from dressing, so your sex life might very well improve.
A quick warning: it's not uncommon for women to react by trying to "out-feminine" him. This will start a spiral that you will find uncomfortable and I doubt seriously that you will win. Just be yourself and let him be himself.
Now you can have both a boyfriend and a girlfriend! With your help, he can fully integrate both sides of his personality and become a human being. You just might learn a lot about yourself along the way.