Help about my son who is four how do i explain to him that he aint a peadophile?

Ok i noe this sounds so stupid but this aint a joke. i noe this is all my fault but no mother is purfect, plz dont tell me im a unfit mum coz i luv my lil boy to death i just did a mistake ok and need help! ok heres my story my lil baby boyy charlie is four years old and basically me and his daddy sean were looking after charlie and babysitting for one of seans mates so we was looking after a lil gal called bethany aswell she is fourteen months old. Sean kept saying to charlie that he should kiss bethany and that charlie luvs bethany bla bla bla so charlie kissed her and said he luvs bethany (obviously lil boys will do anyfink daddys tell them to do) and he was kissing bethany and sayin he luved her all nite. tbh i fort it was cute so neva stopped it but then sean turned round and started sayin charlie was a pedo and kept calling him sick and disgusting so charlie stopped kissing bethany and he started crying. i tried to explain to charlie wat a pedo was and he werent one and sean sed he was sorry and charlie werent a pedo and charlie was happy agen but then sean was sayin it agen i wud get mad at sean but wats the point?? we been off and on for four years now and our relationship is crazy, he neva listens to me :'( so anyway sean kept saying hey charlie ur a pedo, he shoewd him a pic of micheal jackoson and was like hey charlie this is u, he always duz the moonwalk lol and says hes charllie, charlie crys but then sean just says hes only mucking abowt and charlie loves sean so much hes happy agen but now hes started crying to his nursery teacher saying hes a pedo and now the teacher has called me in and i dnt no wat to do or say? sean has promised to never call charlie a pedo agen but what do i do??? charlie still gets upset wen micheal jackoson s on the tv or theres a newsreport abwat a peofile and i gota go talk to charlies nursery teacher 2moz and wtf do i say to her???? plz help me im only 17, everybody makes mistakes, i just want charlie to be ok and i really dnt want them to take him of me