<human>: Can you summarize the given text in a few sentences?

I have a dilema. I was cheated on very badly multiple times in my previous relationship, all without my knowledge and as soon as i found out it was over. I'm not stupid. 

So my current boyfriend and i have been together a year and moved in after 7 months, it might seem quick but we both knew it felt like the right thing to do and it still does. When we met i was very open about what had happened to me. We couldn't be happier. The sex is amazing, the best I've ever had and he often says he doesn't want anything or anyone else.

The thing is - and i hate myself for doing it - i looked at his text messages the other day when his phone was left on the bed. I have never done it before and am disgusted with myself for doing it all. I saw that over the last few weeks he has been texting his ex (now lesbian) girlfriend. There is nothing sexual or out of turn about the messages but she has been calling him by what must've been his "pet" name when they were together and they have agreed to meet up one evening in a couple of days time. 

This feels like i have been stabbed in the heart. Despite what happened to me i am not a jealous or mistrustful person, in fact we both joke about how insecure our friends seem with their partners and how good it is we are not like that. I know he has quite a few female friends in his line of work and when he is working he definitely turns on the charm. He is a stunning guy and i have no doubt he gets hit on every single day. It's not worried me before and my theory is 'he's an adult, the charm offensive is not a problem, i'm the one he comes home to every night'

But now I don't know what to do? Help!!!
If i ask him about it, he'll know i have looked through his phone and i'll lose his trust but if i don't i'll drive myself mad because i cant stop thinking about what they might have been texting about since i looked.
<bot>: BF of 1 year is texting and has agreed to meet up with his ex (now lesbian) girlfriend behind my back. Should i be worried.........