Do I get my sister a present?

Sorry if this seems trivial and silly (it is, I know).. but I was looking for some advice on my relationship with my sister. She and I do not get along, she is 37 and still living with my mother. She is emotionally undeveloped in many ways, only has my mother and father in her life, doesn't work and doesn't have any friends. I tried for many years to have a relationship with her but she is very difficult and I have found as she gets older she is just plain mean. Long story short, my parents split up earlier this year and my mother bought a house nearby me and my family, and my sister moved in with her. We managed to get along for about 6 weeks and now we don't talk. I tried to get at least a civil line of communication open with her but it has been really hard going. I have always been the 'bigger person' our whole lives and that is what my parents expect from me, but I have my own kids now and I am really done with wasting time dealing with her. She is going to spend Christmas with my dad and mum and the rest of my family will be coming to my house. I have bought her a small present, despite the fact that she has NEVER given anyone anything. I usually get her quite a few things for Christmas, always have, but this year I am thinking I shouldn't bother. If I do give it to her it will only be out of obligation. She texted me some nasty messages the other night asking how dare I tell my dad that I thought her dog needed obedience lessons, and was really mean. SO I am thinking if I give her a gift now, its just like saying 'Its fine that you treat my like crap all the time, here's a gift". What do you think?