I completely felt the same way.  I remember feeling guilt because it felt like i had my life back and even lost all the weight gain.  But then I realised miss 3.5 didn't have any cousins and was very spoilt by us and my mum.  Now that he's here, I couldn't imagine life without him.  And you'll find the second time a round better as your way more relaxed.  Goodluck and congratulations xx