NTJ! So your wife supports her bro instead of you, and doesn't want YOU to spoil Christmas for her? That definitely shows where her priorities are misplaced. You have a lot of thinking to do in this case. Let your wife go to her bro's house for Christmas, since he is her first priority.
Your 'partner' needs to make a choice -- either you or her 'friend'. Friends do not impose on other friends. If your partner can't see that, then you need to realize that, if the relationship becomes permanent, you will be facing that long-term.