How to tell a neighbor I am a crossdresser?

I have a fairly private place on a lake. I have only one close neighbor. I am a crossdresser and like to dress as much as I can. The problem is that because my neighbor is so close, I am afraid she will see me when she is home. She actually came over once and walked in while I was dressed. I am not sure if she saw what I was wearing before I scampered out of the room. She is very nice, mature and open minded. She lives alone and is a divorcee. I also consider her a good Friend. I would like her to know so that I can more freely dress. Should i tell her? If so, how do you bring that up? I am serious, so please no stupid answers.