Am I sinning by having women's lingerie?

My wife and I have been married for 21 years. Our intimate life has been reduced to once in a while, usually once a month. I like her wearing sexy lingerie, but she doesn't like it because it makes her feel uncomfortable. I asked her about me gettimg some for me, and she didn't mind the idea. I am not talking about womens stuff, just satiny stuff intended for men. I looked around, and most of the stuff I found was extremely expensive. I found a site online and found some simple stuff reasonalbly priced. it was just underwear. Unfortunately, after I got it, it turned out that is was women's design. I tried them on, and I actually liked it. I didn't know at first what it was for sure. My wife doesn't seem to mind me wearing them once in a while. I got them originally thinking they were men's and have no interest in cross-dressing. Am I sinning by having them?