Do you let your kids use social media

I have two young daughters the ages 13 and 14 and they are both iPhone crazy! The only reason they like and want the iPhone is because all the popular rich kids have them.I had bought them both an iPhone for Christmas last year and the 13 year old broke hers in a month and the 14 year old was making musicallys
to very provocative songs they she had no idea of what the things the singer was saying even meant! After my family told me of the videos i was totally disgusted and embarrassed .I took the phone and told them both they could have social media until they were old enough to pay for their own cell phone bills.They looked at me like I was nuts!!Kids these days are just too cruel to one another and they do not think about what they are doing until one of their classmates commits suicide.Its awful! Now that school has started both girls are bugging me to let them have social media again....what do you guys think?Should I let them have it or should I continue to be the uncool dad and say no?When they are older they will understand that I was just trying to protect them,but at the same time I do not want them to re belle against me.Let me know if you have been in this situation and if so what did you do and how did your kid react.