If it's the pressure of all those people, and it being the holidays, rather than visiting your mother that's the problem, then perhaps you could apologise profusely to her that you can't make it and promise an extra visit sometime when she might otherwise be on her own. She'll have others around at the holidays to keep her company.
Years ago I made the decision to stop going home for Christmas and start a new holiday tradition with my family in the country I now live in. We have a lot of Skype video chats over the holidays, and we visit in the Summer instead, when it's cheaper, the kids are out of school, and there's a lot more to do. It was weird at first, but it was the right decision. In your case you do sound you have even more reasons why not going back makes the most sense.
Whatever you decide, I hope you'll hang tight to your sobriety. Early days is the hardest time, but it's very, very worth it.