So if the OP was in their company, but in the country the originally came from, it would be fine for them to exclude her? Or do you think if she was in there country, she should onky then have to learn to speak their language? actually yes I think that she should learn another language if she lives in the country of that language.
But TBH most people aren’t rude enough to exclude the only non speaker of their language if they speak that person’s language even in their own country.
For reference, I grew up abroad. I attended a school where another language was spoken and as such I learned to speak that language and now speak it as a first language iyswim i.e. my fluency in that language is exactly the same as in English.
But my parents don’t speak it, and when they spent time with others who spoke it, including my friends and their parents those people spoke in English as it would be rude to exclude my parents.
I still have friends in that country and they occasionally call me, and although we could technically speak that language they speak to me in English, even over the phone as they consider it would be rude for me to be sitting talking to them in another language while my DP and DC look on.
But in the OP’s case the family have chosen to move here. As such it is not unreasonable that they speak to and in front of those who do not speak their language in English.
As for saying that the OP chose to marry a man who’ speaks a different language, presumably they got together because he spoke English because if he hadn’t they wouldn’t have been able to understand each other.
We don’t justify family excluding one person for any other reason, this is no different.