I've been dating a guy I met online for the last 11 months. We hit it off pretty well and things have gone quickly. It's not been without its problems, mainly around our respective dc not gelling very well but I've been very happy and could see a good future with this guy who I thought was very different from most (I know everyone thinks that).
We have both been cheated on and lied to in our previous relationships and BF made it very clear from the outset that he expected complete honesty from both of us. He even specified that he expected to be told if a guy had tried it on on nights out. And I duly obeyed his wishes.
However, over the weekend (which was a bit difficult because we had to have some in depth discussions about the future due to the DC's issues) he told me that he had bumped into an ex and she'd since been messaging him asking him if they could meet up etc. I'm not a jealous person normally and I trusted him implicitly so I wasn't too bothered but something irked a bit but I put it down to the fact that we had been having difficult conversations about the future.
However, he called me from work today to say that they didn't just bump into each other - she had invited him round to collect some stuff he'd left there (over 18 months ago). This was apparently a ruse and she had tried to kiss him. He says he pushed her away saying he had a gf. She has since been messaging him (not sure by what method as he told me he blocked her on facebook and he got a new number in the last 6 months) threatening to tell me that they'd slept together.
He met up with her last Wednesday and has only just told me this today. So he's effectively been lying since then. I have thought back to that day and he was let out early from work and called me to tell me that he was on his way. But he arrived much later than he should have and when questioned, said he'd bumped into a colleague and visited a friend.
I've asked him to send me screen shots of the messages between them but despite saying he would, he's not sent them through. I've also checked my other inbox on FB but she hasn't sent anything. He says she knows who I am but doesn't understand how 
. What makes this whole thing worse is that this isn't the first time one of his exes has threatened to tell me they were sleeping together behind my back.
He's adamant nothing has happened but it doesn't look good does it? I already feel betrayed by the fact that he delayed telling me and only did apparently as a reaction to her threats. Ive also lost a lot of respect for him since the lying has shown him to be a hypocrite if nothing else.
Not sure why I'm posting really. I'm hurt and feel like a fool for believing he was in any way different. But I'm not afraid to be on my own. So as in the title - what would you think in this situation and what would you do?