Can you ever recover from being cheated on ?

my partner of almost 2years has been txtin another woman.
Things were great between us until Xmas and then things/behaviour changed,he became less affectionate the intamcy dwindled and it seemed he could barely bring himself to talk to me, I had a gut feeling something was going on and thought it was his ex wife, I looked through some of his social network messages and found several flirty messages to other women but they seemed uninterested, whilst this made me angry and feeling sick nothing had happened as of yet and didn't want to give away that I was snooping which I felt guilty for.
I managed one Sunday to get hold of his phone and what I saw brought me to my knees some very explicit messages of what he wanted to do to this woman and how they had tried to meet up but as far as I could make out it hadn't actually happened. I confronted him and asked him the usual questions and he promised me nothing had actually happened but the messages I feel are just as bad because if someone is happy with the person they are with why would the do that, his excuse was attention seeking and that he would never have actually done anything but I find that hard to believe I think it didn't because I found out first, we decided that we would try make it work but I'm struggling when I go to bed all I see is the messages, when he goes out I'm finding it hard to trust him, I'm still going through his messages and I think he knows this as all messages are deleted I do love him but I don't want to be a doormat I always said if someone cheated I'd be gone but once your in that situation it's not always that easy.
I trusted my gut instincts and I was right to only trouble is now they are back but I've got no evidence to back it up I have asked him but he has denied it as he did before but he lied then what's to say he's not doing the same but has become better at covering his tracks.....any advice welcome