I was just talking to a PC friend about this today. Weird!
I'm not married so I don't really know if its healthy to keep it from a husband (because I imagine the best of those relationships are open and if I had something to discuss about a session - a husband would be who one would tell). But, i'm not married and don't have that issue.
I do, however, live with my family and have chosen to keep it a secret from them for many reasons - 1) it would never stay a secret if certain people found out, 2) they already look at me as weak and babyish, 3) they already think of me as 'the crazy one', 4) they may disagree with my choice of T and try to pit me against her {for superficial reasons}, 5) I would probably be discouraged from 'wasting money' on it, and the list goes on.
I did tell my father, mainly because I had some questions in the beginning that needed answering and he was uncomfortable providing me the information. So he knows but he lives ~16 hours away and we never discuss it so it's not big deal.
The awkward part is that my mom is listed as my emergency contact and she doesn't even know that I'm in T to begin with. Anyways, T knows all of this and she told me that 'there's no rule that says you have to tell your family you are in therapy' so I assume it's not unhealthy or unusual at all.