You think his cheating part 2

Hey girls well yesterday my husband ans i were talking to my sister over the fone using headphones and by mistake he pressed calls well guess wth that girl was calling him at 4 am I was in a shock he said I'm sorry but it's not wth u think and he sent her a message telling her please do not talk to me again outside work and ill be professional with u from now on and she said to him ok but can I ask why he said cause I'm devoted to my wife and she said as u wish ... well I told him if u guys like each other Im happy for u he said that he would never do somthing to hurt our marriage and that he loves me bla bla bla

I dnt believe him and I just want to be out of this relationship ASAP thank god I dnt feel angry ..I'm cool abt it and I believe and wthever god gives me..

So wth you guys think I should do

FYI I'm a cool girl and I never stopped him from having girl friends ..