how do you hide only a status and not the entire wall on facebook with the new privacy settings?

[ashley]

I made a tiered profile limitation category. I have regular (un-restricted), moderate (semi-restricted), and limited (mostly-restricted).

I would suggest doing the same and putting your boyfriend's mother into that category. You'll need to create the category first, then go to Privacy > Profile Information and set which category can see which part of your profile. The listing you're looking for is "Posts By Me" ("Status Updates, Links, Notes, Photos, and Videos you post").

Hope this helps.