pathetic situation

i luv my bf mor dan my lyf.we are in a relation from last 2yrs.he works in d same office dat of my mum.my mum is saying dat he is havin affair with a 40 yr old lady of dat office.there is a world war 3 going on betwn my mum n him.now he got fed up by all dese n has stopped taikng 2 me.i have full faith dat he doesnt have affair with dat lady.he has helped me in in every difficult situan of my lyf.i dont wanna loose him.plz give me sum suggestions.