Mom getting on my nerves.

 Everything I tell my mom she'll turn it around and use it on me. I've been holding it in but this recent comment irked me so bad. Okay so my fiancé has a 6 year old daughter from a previous relationship who lives with the mother who we barely get to see (whole other crazy story) and we have a 9 month old son together. I just haven't had the time to put our Christmas tree up with everything going on but I didn't see it as such a big deal seeing as there's still 5 days still till Christmas. 
My mother on the other hand thinks it's so bad and said "how are y'all not going to put a Christmas tree up all because his daughters not going to be there, it's your sons first Christmas worry about him not her y'all can worry about her when you're settled down!" 
I'm steaming and just don't even want to talk to her. 
She doesn't think she said anything wrong.