Relationship problems, any advice?

i'm 23 weeks pregnant and having problems with mine and my partners relationship. A few days ago I found emails from his ex girlfriend when I was picking up an email to sort out his health insurance. They were on facebook and he didn't realise an email is sent to your hotmail aswell when you recieve a message. They weren't anything bad really just the usuall chit chat and he did mention when she asked that he was in a relationship, but the thing thats upset me is that he told her he was thinking about going travelling for a year.. I asked him about this and he said he didn't really mean it, but alot of things in the email were rubbish, he lied about where he worked, it seemed he was trying to make himself look better. he also changed his facebook pword and deleted the thread so i wouldn't find out about the emails, but i saw them through hotmail and clicked on show deleted thread. nobodys known about this pregnancy til recently because we had twin girls die last december.