<human>: So I'll keep this short and simple, because I feel I am in the right, but I guess I just need the approval of internet people and to justify my actions. And some of your advice is actually really good in this subreddit.

So my gf and I have been dating for 2.5 years, and I believe around April sometime she met this guy and they went out on a date behind my back. I knoew about the guy, but not about the date and he ends up leaving the state for about 4 months. I didn't find out until about August and I had asked her if she still talked to him (I wasn't too fond of him) and she said "no". I left it at that, but around August sometime I see a mysterious text from a name I don't recognize, turns out it was him and they had been texting, snap chatting, FB messaging, whatever the entire time....blah blah blah some arguments occur and she lies and lies...but we get over it, and she promises to never communicate with him again (this is important for later; and also I still do not trust her)

So turns out, she still snapchats him months after I find out, even though she promised never to communicate with him. And just last night I found she sent him a snapchat, even though she told me it was an innocent one (a pciture of the sky, or her dog I don't quite remember). But that's not the point, she lied and broke her promise even after breaking my trust earlier in the year. 

So reddit was I wrong to call it quits after an innocent snapchat, but a huge broken promise? Also, this is not the first time; I believe we are past the point of "talking it out".

Can you condense the text into a few key points?
<bot>: gf texts some guy for months, I catch her, we fight, she promises never to communicate with him anymore, and then I still catch her snapchatting him quite frequently. Was I wrong to end it?