Help? are we over reacting? Friendship breakup.?

So i am guy and i had like 4 friends. its me , my guy friend and 3 other girls. we are all really good friends. we seen eacheach other as family. but one time i wsd hanging out with my guy friend. we were alone and bored at a carnival so we asked one of our girl friends to hangout with us. she was down to come hangout with us but when she found out that was only us 2 and not the whole squad, she laughed at us and said "lmfao only yous 2"? and we said yeah why? she asked if everyone was coming and we said no they were busy. that s when she said nvm some other time then. she send us off only because it was just me and my guy friend. why does it matter if its only us? we have been good friends almost 4 years and for her to say that or send us off like that. it made us sad that she was never a true friend. so we got a lil upset and we left a group chat we all had on snapchat. we did to see if she would ask us whats wrong , or to ask why we acting weird. to check up on us. she didnt bother. to us it seemed like she didn t care if we stopped talking to her. after that we just deleted her off any social media. she still didn t bother to ask us anything. she doesn t care about us. she doesn t care if she looses us. if she was a true friend, she would try to fix the friendship. WHAT SHOULD WE DO? we really miss our friendship we had with her.