Is my older sister manipulative? A narcissist?

[aboy1995]

Long story short, my nephew absolutely adores me. Growing up, no one bothered to pay any attention to him or wanted nothing to do with him.... until I stepped in over a year ago. At first, my sister (we don't have the same dad) was very accepting and happy that I started to include her son (my nephew). Months go by, and she starts to slowly tell him that I can't do this or that, and she then takes him away from me for periods at a time. Just this past weekend, she told him that he was to completely block me off of any social media, my number, and even off of his gaming console. The reason you may be asking? Because he's "too attached to me". Well, not only that, but I had made a joke at a birthday party over the weekend that I, "didn't have to listen to her since it was MY DAD'S birthday (Rip)". She took this joke to the extreme and has turned quite a few people against me, my mother most notably. So, what do you guys think? I will be 1000% honest and say that I don't talk about her negatively or anything. I feel like since my dad has passed, she just treats me so poorly and has been doing anything or using whatever she can find against me.