I came out a bit too harsh. Just from personal experience, none of my relatives are religious and I had to “miss” my cousin’s marriage because they guy she married wasn’t a Jew.
The message I posted was sort of what I was told by my Rebbi. It still is awkward every time I see her. So I sort of know where you are coming from. Except my relatives way of dress doesn’t bother me too much.
And if I understand correctly your relatives look down on the orthodox way of life. That is tough. Only thing I can say to that is do your part by being nice and friendly and in the end they may reciprocate. Its not much but toughen your interior.