That's not my name

Me and my husband of three years we're having sex this morning before he went to work and he mumbled "Oh, Ash" before he was about to climax. My name is Samantha. He says "Sam" a lot while we have sex but this morning he said the wrong name. I was like what?? And he acted like he didn't know what I was talking about.

Well there's this girl on his Facebook named Ashley and she's been commenting on every single one of his pictures but he never says comments anything back and he claims he has no clue who she is and he says he's never messaged her. I believed him but now I don't know..

And he's been working a lot of over time here lately but now that I think about it his paychecks have been about the same as they always are. I don't know if I'm over thinking it or what but I feel it in my gut. And I have no way to check because I don't know his password to Facebook and his phone has a passcode and I can't really follow him to work or anything (not that I would) but because we share a car and that's what he takes to work. How can I find out? Help me please I'm having a panic attack I feel like my heart is broken I want to know the truth