I know you want to be strong for your mother but don't forget about your needs. You are definitely going to need support from friends, family and your online community. Don't hesitate to reach out.
So sorry to hear. In 2005 I nursed two very close family members through cancer. That together with three kids and a job almost destroyed me and took me over three years to bounce back. If you c an do your surgery now, go for it before things get really hectic. Best to you and mom.