I can't strees enough how important that is. It took me a while to get the courage, and i actually tell her on a shoe by shoe basis and she doesn't have a problem with it at all.
It started with me buying a pair of ankle boots that had a 2" block heel and a square toe, from eBay, they were listed as a mens shoe, and thats what i thought. i showed them to her and she thought they were cute. when i researched them a little more i found they were womens shoes. I told her that and she said "i don't care if you wear girl shoes"
I still have to work up the courage to show her a new pair but i feel comfortable doing it. When i pick out my shoes (mostly boots) i pick ones that i can still be confident as a man. I am not a cross dresser or anthing like that, iam a man that enjoys wearing and likes the look of heels. Cause lets face it, mens shoes are boring:-D