<human>: I am devastated. Yesterday heard my GF on Skype using her "sweet voice" - which she only uses with people she is intimate with - and happened to hear a date and an amount of money which made me think of a plane ticket.

Asked her about it, and she said she was planning on going to an event for the day with her friends. Didn't mention the amount of money, only that I heard the date, and she never mentioned this either.

I know I fucked up but the way she answered seemed like I caught her off guard, she blew it off in a very unnatural way and it made me suspicious. I snooped on her browser history. Saw she was looking for plane tickets to Montreal, where only his ex is. No other friends or familty there. 

Do I bring this up or cut the trip short to get back earlier with some random excuse and then catch her when she gets back? For all I know I gave her a scare and she cancelled. But I know my trust is completely broken now. 

How the hell do I handle this?

Can you condense the text into three sentences or less?
<bot>: GF secretly planning trip to see ex while I travel to work, coming back right before I do. I am broken, what should I do?