He's talking to his ex

Megan
So over the weekend I found out my boyfriend has been texting his ex. I was sleeping right next to him whilst he was and he told me he was texting his best friend. He's told me why he was talking to her and that was because she messaged him really upset. I also found out by going onto his emails he had asked her to go round his house whilst no one was in and I was at work. 
I honestly don't know what to do. I've talked to him about it and he's told me he made a mistake and shouldn't have lied to me or asked her to come round. I don't know if i can trust him again. 
What would any of you do in this situation?