How tell if she is telling the truth or not?

i only have circumstancial evidence.but to many cases! and she can walk into a chapel or church and put it on all three of the kids lifes she never cheated or lied about the evidence, im hurting so bad inside,its like a mystery where u need to kno the truth to live right, she says im crazy n stuff ans treats me like ****. and everything amaginable to make it seem like shes talking to someone else! but the whole church thing i wanna belive,n she knos thats the only thing holding are relationship together. and i also kno girls are cold,,,,,sooo cold! and will lie till they die! is that true?