What to do with this ****** of a friend?

My best friend and i have known each other for about 4 years...I've learned to deal with her PMSish behavior over the years and i would honestly do anything for her without questions when she asks me to...since she's rekindled a new friendship we all try to get along and hang out...the problem is whenever we all go somewhere or just them two go somewhere her new friend ALWAYS expects rides from me and even my parents even when I don't even know her...Also my friend has gotten twice as grouchy and annoying around me since she's gotten with this friend...they always get angry and make fun of me whenever I don't tag along with them to do stupid things and bash on all the things I like.