I just started dating someone who is newly embracing poly himself. During a conversation, he checked with me to make sure it was okay to mention that he has some other dates set up. I told him that, of course, it was fine. He then told me he felt a little guilty that he had these other dates, and that he was still looking on OKCupid, while he is also dating me. He acknowledged that it isn't logical, but I was glad he talked about it because it lets me see a little bit more into who he is and how he approaches relationships.
I think it is only natural after we have been conditioned by society to be monogamous and focus all our attentions on one person/partner, that it could be a little disorienting or unnerving to have the freedom to focus on someone else. Be compassionate toward yourself, let go of any self-criticism, and just go and have a good time. Be sure to acknowledge your hubby for how amazing, understanding, and loving he is - and you'll be fine!