I need help please read this?

i got a boyfriend and my friend use to date him but i think that she still likes him , me & my friend damaris went to his house and I usally dont go to his house and one day she went in a& i wuz waiting for her outside & i ask her" why did u take to long inside?" she said " i wuz only talking to him for a sec" then she said " Rudy ( my boyfriend) said to go inside" so i went inside for his house then i told her to wait for me outside cuz i wanted to talk to him in private so i told him " dont be cheating on me wit my friend he said he would nevr do that but i really know if my friend is really my friend becuz she would go to his house behind my back