Hmmm the girl has some serious problems but otherwise if she is a good girl like if he truly loves him and is faithful to him then he should have a talk with her and tell her that how much her abusive language & her possessiveness affects him. Let’s see what she has to say then. If she show willingness to change herself for him then it’s a good sign and they should start working on it. If she does not cooperate and does not show any willingness to change then I think he should say goodbye to her. Swearing is something I believe she has seen since her childhood , for so many people it’s not a big deal because they have grown up seeing people swearing at each other but people can change. My inlaws very frequently used words like zalil , kameena for each other too and it was normal for them lol !
One thing that came to my mind was that how much controlling the guy is ? may be he is same way or even more controlling and possessive than she is and what ever she is doing is in reaction to his behaviour.
It’s better for both of them to discus things out before ending the relationship. Always give relationships a chance before ending , you never know what you might loose in a hasty decision.