I think you should change your name to your DH's name legally and continue to let people (like your DS's school people) call you by your DS's last name if it's too hard for them to remember you have a different last name. On his emergency card, though, you should put your new last name. They will figure it out. It's very common. For work, you can hyphenate it - with your ex's name first and then your Dh's name last. That way they will still recognize your name, but know that you are married to someone else now. Or you can just change your name to your Dh's name and when you change jobs you can let them know your old name, to for references KWIM? Women change their names all the time. I think people will understand. I think you can change your name by mail with Social Security. You just download the form off their website and send in your marriage certificate (it has to be the original, not a copy) and they will send it back to you with your new card. Then when you get that back you can go to the DMV. I know the SS office really sucks, but the DMV isn't as bad. I don't know about the Fullerton office, but I know the Costa Mesa one goes really quickly during the day. I recommend going to the Costa Mesa Dmv.