Non-observant Jews and the non-Jews who marry them…

So what am I supposed to say when I find out a chick in my class is married to a Jew and her mother in law is giving her a hard time about the fact that she is not Jewish??? I make no secret of the fact that I am an observant Jew, very hard to hide when you are freaking out trying to finish all your work on non-existent weekends due to Yom Tovim (holidays).
I admit sometimes I will be in your face, when you are being inappropriate or saying things that are blatantly false I will call you on it, no we do not make matzos out of blood!!!! But how to deal with the every day?
When I found out about the intermarriage I said something along the lines of the in-law wanting to have Jewish grandchildren and since the religion goes through the mother she is upset and coming to terms with it, was this the wrong thing to say? I was not being confrontational just trying to point out what is probably going on in her mother-in-law's head. Should I have kept my mouth shut?
How about the brother’s girlfriend, what am I supposed to say to him. He gets annoyed when I ignore her; well I was not ignoring her only greeting my grandpa and aunt first, what is wrong with that? I talk to her when we are in the same room and all that, I’m not rude, well perhaps the better way to say it is I am polite! He knows how I feel, he has known how I felt for years now, why is it always such a surprise to him when he asks and I tell? The answer does not change. For a smart guy he is acting stupid. He always thinks mom would have sided with him, here is my proof… in her letter to us, the one we received a year after her death, she said that we should both marry someone Jewish. Ummmm, your so right A she would back you up 100%!!!!
Ok, I am taking a deep breath. Oh by the way I hope everyone had a meaningful and worthwhile fast!