Viktoria,
First off, I don't think it's fair for anyone to belittle you for having your own emotions! Second, I don't really consider that cheating. We had the same issue after our second baby. I was pooped, I was nursing, I'd had my second cesarian and was really sore (didn't feel like having any weight over me). I caught my husband doing the same thing. It really hurt my feelings, but then I realized he needed his own release (mine was dragging myself to bed and nodding off as soon as my head hit the pillow!).
So . . . I told him to be smarter about it, at least. Wait till I'm ASLEEP! Clean out your history and your cookies so I don't know that you've been looking. : )
And when we were intimate (probably once a month like you until the little one was a year old, and I started to get my drive back) I made sure at least a small light was on! That way what he sees it what he gets (or is getting anyhow!).
You sound like a wonderful woman, with a great husband. I wouldn't worry about the websites, but would tell him to clean up his . . . history, etc. ; )
Best Wishes (and don't worry, you'll be in the mood after your body gets back to normal, and you get some rest!).
K.