You don't. You have known for over a month about this event. You should have been planning and looking in the closet from the first time he mentioned it and had written it on the calendar. After that you should have gone through your closet after looking in a magazine at what the stars are wearing and created an outfit. It doesn't take much to spruce of a pair of jeans or a nice pair of capris of something and find a top you haven't worn in a while. Learn how to do your own eyebrows and hair since the budget(s) won't allow this. Be practical and frugal.
I can't think of how many times I wished I could have someone do these things for me but I just learned how and now I have only person to blame if my hair doesn't look right ME.
What you are doing is telling your husband that you don't want to be around him or with him when he wants to go out. If you don't put your butt in gear and do man/woman things he WILL find someone else to share them with. You don't keep a marriage together by staying home you have to get out and be an adult not mommy full of dribbled on clothes and barefeet.
Sorry it time to be a woman again. Remember you were a woman, wife and mother in that order. Work on your marriage and be a woman and wife again. You will be surprised at how thing will change around. He may even start helping you more at home with kids and "honey dos." Got to think outside the box.
You live in a big city. Do check Goodwill if you have to find something in the closet. I bet these people don't know what is in your closet. Just make yourself look good. Trim the wild brow hairs, get the curling iron out and wrap a few strands around it near the face to soften your look. Put on a little makeup and perfume and call it a night and enjoy yourselves.
The other S.
PS He does understand that women like to look good when we go out. It is just how you go about it.