What do I dooo?! I feel embarrsed.....?

I posted to my older friend (Year above me,we have diffrent sets of friends)"Please don't put those pictures of me up!" She commented say hahah I then said "You ripped your trousers! lol!" She said she got them from Primark and said they were expensive,I said "Really?! The shoes cost like a pound" she said she was being sarcastic,then her friends got funny about it and said no atualy they arn't a pound,the insoles are �2 the shoes cost �4,I said I don't know but its cheap,then blah blah then I said Primark is crap,they said it wasn't,I said it was and slave labour,they got funny about it and said they chose to work there,the poor people and I explaned to them that people out there have to or eles they die of starvation,how they work in poor conditions ect,then they asked if I was their Geography teacher,they said they didn't want a HIstory lesson.I feel really embbaresed now :( What do I do???