Hub and lover?

I love very much my hub but I didn't have his attention lately, he was often tired, this is why I started an affair about a month ago. But our relationship is become much more better in bed since two weeks , he is sooooooo good. My affair was platonic till last week when it become real. I didn't expect him like that, I thought he was different my lover made love to me in a such sweet way ... and I don't regret anything but now it seems like my lover act in bed as my husband and my hub as my lover, and this is confusing. I'm taking time from my lover now..What should I do? I don't know how to tell him without offend him.