I can completely understand having something that was possibly traumatic in your past that isn't easy to talk about (I don't understand why PP just assume it's something scandalous or something you're just embarrassed about....) so you haven't shared with DH. There are a couple things in my past that are so traumatic that I have only disclosed with my therapist and left it at there.
However, if it IS a traumatic incident that happened and you associated THAT name with THAT incident, would you want your sweet little baby to have that? you can't always help if you project feelings onto other people..it's not always something you can control....and you don't want that association with your baby. if it was traumatic, I would find a way to let DH know. Even if it's hard to talk about, because you don't know if there could be repercussions later on in how you project your feelings from that event onto your baby (it does happen).
If it's not a traumatic incident, and it is something you're just embarrassed about...talk to DH about it. Get it out there, let him know how you feel. you may find after talking about it that it wasn't that big of a deal and you can accept the name.