Calm down with anger part first& remind self - all the good things u guys did together & love u share. Let them apologize and reassure u that it will not happen again. it can be a simple mistake on their part which hurted u deeply!! Peace & healing for u lady :)
You can still win. He's somewhat of an idiot if he thinks he can win an argument with a woman by using another woman. Appeal to his sister's better nature! You're a female, you got this.
This is why I never argue, I talk. If voices are raised, nobody listens. If insults are thrown, all they do is hurt the one they supposedly loved/liked. If you can't just be honest with each other and talk out your differences, all it's going to do is make things worse. But that's just my 2 cents on it.
oh dear lord, how old is he??
there have been a lot of boyfriend with sisters questions on here today
So immature. You two do not need to be together.