i agree. i felt when reading this that it sounds like some of those girls are a little jealous of her and worried that her relationship moving to the next level will change the group dynamics. idk what the history is, but if the friends hate you it's probably a combo of them not letting go of past stuff she's told them (like the drunken night at the friends house) plus being a little envious that she's happy in the relationship now (which is clear from the current texts of hers you saw). she's been friends with them too long probably to notice the envy or leave the group. you need boundaries with the friends and to tell her how uncomfortable it makes you feel. it's not necessary for everyone to be super close all the time.