Am I actually in the wrong?

Me and my babies dad have been split for a few months. Recently he's been saying he wants to get back with me and I decided to give it a go. He came around today. We were chilling and he asked if he could go on my phone and I said he could. He asked for the password and I gave it him. He went straight onto my Facebook messages but I didn't try and stop him because I had nothing to hide. Since he has been saying he wants to give it another go I've had tons of messages of guys and I've ignored them. There were conversations from when we wasn't even together but I didn't think he would care about those because we weren't together and it's not like he hasn't been with loads of girls since we broke up, I had just been talking to people. He came across messages from about a month ago from a certain guy and yes I was pregnant while I was talking to him but the thing is I was still single and I wasn't even in touch with him at this point. As soon as he seen these he went off on me saying I was a hoe for talking to him while I was pregnant and that he's not getting back with me now. I said fine then, I don't see what I've done wrong so carry on. He's slept with loads of girls since we've broke up, I'm not saying to him that I'm not getting back with him for that am I? Because what happened while we were not together is irrelevant in my eyes. Am I right to think I haven't done anything wrong or is he right?