Christmas for my children

I am looking to buy Christmas gifts for my children. I recently moved to Binghamton, NY from NYC thinking that I would be giving my children a better life. I haven't been able to find a job. I've applied everywhere that says hiring and even places that are not hiring. I haven't had any luck and Christmas is almost here. My children have been very good this year and believe that Santa Claus is coming. I don't know how to tell them that he's not. I don't know if I should tell them that there isn't a Santa Claus. I feel like I really messed up. I need help. I've been selling my clothes on letgo and offer up to buy food and pampers. The only semi-peace I have is knowing that my rent is paid until March. Anything helps, please help me.