I have namechanged 
I don't know what made me look (I don't usually) but I looked at dh's messages on his phone this evening.
There's a message off an 'unknown' number saying "hey babe u free 2night im horny and want u inside me" It was sent at 9:09 this morning. I'm devastated 
I would never, ever ever believe that dh would be unfaithful. And actually, I'm not sure I still do. We don't have a great sex life, that much I have to admit, and I suppose that is what is worrying me. But I really really can't ever see that he would cheat on me.
Apart from anything else, he works so hard (outdoors, in all weathers) and he is home regularly every evening. He very rarely goes out, and I really can't see how he would have the time to cheat, even if he wanted to - which again, I really don't think he would.
Or am I being incredibly naive?
He's in bed right now, so I can't ask him, but how would I ask anyway because he'd know that I had been looking at his phone 
Please give me some advise - I'm devastated 