Is it ok to insult my brother's girlfriend because of a Christmas present?
That seems rather cruel. Why would a Christmas present make you want to insult her?
Because she deserves that for stealing my brother away from me.
You shouldn't insult your sibling's partner. If you do then you'll end up creating tension between all three of you. Try talking to your brother and tell him how you feel and maybe he'll spend more time with you.
Well maybe I'll do that. Then again, I'm a disgusting person who can't be happy with other people's happiness.
I really hope you do take my advice and talk to your brother. It's understandable to miss spending time with him, but insulting his girlfriend will just make him want to spend even less time with you. You should explain how you feel to him and try to get along with his girlfriend.