<human>: 24m, have been together with my 23f SO happily (bar the usual couple problems) for a little over 2.5 years. I'll try to keep this brief: 

What happened:

* Snooped (I know, not cool) my SO's facebook on her mobile, found a long convo between her and her ex. Didn't read much of the conversation as I wanted to see how much they spoke. 
* They spoke quite a bit, as I scrolled up a lot and all I saw was only from a day.
* Found a way to hint at it without bringing this up. She said she wants to be cordial with him, they only spoke briefly, and told me I had nothing to worry about.

The problem:

* We've had a chat about this before, and she agreed to not keep in touch with him, as it makes me feel uncomfortable
* I saw the convo, there was nothing brief about it
* She also told another lie: I asked her where he is in the world, she says she's not sure, when one of the things I saw was him saying "let me know when you're around here" -granted it's halfway across the world but she does have recent plans to go there.

Where we stand:

* She's away on holiday (I found out the day she left, which is why I didn't want to talk about it as I thought it'd ruin her trip) and will be back tonight. Will probably be tired, so I'll bring it up when I think she's ready.

What I wanted to know was how do I approach this nicely? I don't want to seem controlling/tell her what or what not to do, but at the same time I really feel like I've been lied to and I don't like that she does things behind my back. Some help please reddit. Thanks.

Can you provide a brief rundown of the text in within 3 sentences?
<bot>: Snooped and found SO talking to her ex, when we've established that it makes me uncomfortable. How do I talk to her about this?