The Man I love who is also my thinks I slept with his Best friend.?

I Was With this guy for a year thing got rough so we broke up due to unfaithfullness and dishonesty on his part. but through out the next year I dated one guy and didnt work out cuz i was still in love with my ex. so we've talked here and there but never got any where. So his friends are also my friends and i hang out with them likeonce a year well I see one ofhis friends and we exchange numbers and he invited me to a party so i wentdrank alittle but all me exs friends showed up andsome family and some girls that hated on me for some reson. guessing having something to do with him. but the whole night everyone let me know he was still in love with me and that was a relife cuz iknew he still loved me too. so the nextday me andmy ex got to talking and things were going good and someone toldhim from the partyi had with his bestfriend and other things like i get around but i just got from colloge like4 days ago so i havent been in myhome town. anyways my ex wont even lsten to me and decided to take thesepeoplesword over mine. Never in a million years would i do somethinglike that i wouldnt do anything o hurt him or disrespect him or myself. so i need to know how do i get through to him and how do i make him understand thateverything he hear isnt true i dont even live in myhome town.