I have no clue how to handle this situation. Please Help!?

[Tessa]

It's obvious why he's doing it...to get to you and it's working....and some how he has convinced his new girlfriend to join in on this devious plan...he probably bad talked you to her and she feels as if she has to rub it in as well...
The only thing you can do is express your uncomfortable feelings to your brother and who ever else that they have befriended..tell them that you would like it to stop if possible out of respect for your feelings on this..the ball then is in your familys court...you cannot control what they do ..just ask...
meanwhile don't react to the ex or the girlfriend it will just feed there purpose...