Ooh, it's better to not rely 'just' on family for emotional support... It may be nice to have, and in some families it happens, it's not a given by all means... Your sisters may be preoccupied with own lives or angry cause you didn't do the dishes or such, or cause their tire went flat or they might be unhappy with their job or something... (These are just examples, it's different in every family...) Maybe they just had a bad day... Some people can also get preoccupied or even overwhelmed by own problems or plans and don't really want to listen to other people's...
When they have friends over, they may wish to come across 'well', and may want to make a good impression on the friends... Or maybe they were even trying to be helpful and introduce you to some people? If you've just met someone it's better to talk about more 'light' themes, like ask 'Where have you two met?' if it's a new person, or ask about that person, where are they from or talk about what they like to do or have recently done, have they seen any good films, or give maybe a compliment like 'nice hat' or even talk about the weather if it's necessary...
Talking about sa would usually be reserved for people who know you well and you know them well and know you can trust them... Or in a support group or such...
Your sisters' friends are not a 'support group', if you like some of them and 'click' with them (=they like you back), you could try to maybe become friends with them - slowly!! it's better to start with common interests though... eg what kind of films or music they like, what kind of things they do in free time etc.
It's also better if you can find your own group of friends, to not rely on your sisters', especially if you and sisters are very different...
Maybe you could even ask your sisters what would be appropriate to talk about with their friends?
Many 'social' people may not understand sa... so maybe you could just say you're 'shy' if needed?
People can see 'rude' as very many different things... for some, ignoring them or saying the truth can be perceived as 'rude'... sometimes misunderstandings can happen... Sometimes I've been totally misunderstood too, and the other person/s didn't want to listen...
You can try to make 'good' with people... And/or find friends/support in other places... Is there a support group near you?