Hey all, bit of a long read, my apologies but I don't know where else to go.
Okay so as you know me and my GF had some troubles. We spoke about it a bit and I just said I would give her some space if there was nothing specific wrong.
This seemed to work, I didn't make any attempt to contact her and about 25/6 hours later, she text me saying "Hey

". 10 minutes later when I got the text & started to reply she sent me another text saying "Don't ignore me

xx" We texted back and forth a bit then went to sleep, she said I love you first and said playfully when I said I needed a shower "Oh so when I decide I want to declare my love you run off and shower

", so was fun, etc ..
I left it again for another day, and late at night she text me again saying "Nice of you to bother texting me today :/". I was actually having SIM Card problems, so I told her about them. We text back and forth a bit again, and it went okay.
So I text her during the day the next day, thought it'd been long enough. Her response wasn't great, so I decided to leave it again. Last night she made contact with me again, we IM'd for like, 5 hours. It went badly to begin with, she had an issue with something, we spoke about it calmly. Then things went really well, lots of banter, lots of laughs, told her I loved her and she said it back. When I made a joke about "You'd miss me, more than you care to admit" She said "Oh dw I'll admit it, you think I haven't felt pain for the past few days <continued to joke about it a bit>" - this was a good sign, she opened up which isn't something she likes to do. End of the evening, she even started to become quite suggestive about sex "Oh you like shooting do you? What kind of shooting" I said "Whatever is necessary" She said "Oh well I know someone who could do with a good shooting and wouldn't mind at all if you did it

"
-----------------------------------------
Okay, so she's been at work today and I haven't made any contact, waiting till she's home. But then I looked at her FB, and saw a long conversation between her and some guy she clearly knows. I don't care about this normally, but the conversation went on for a while, it ended just as me and her started having fun talking. And there were lots of suggestions about meeting up for a drink at his place, the fact they need to text each other more, when he mentioned they could do it next Saturday maybe she seemed really open to the idea, saying it "was a good plan" and it's better now "he's given her time to get ready" or w/e.
Okay, so they're class-mates from last year, but this conversation seemed overly-friendly really. Was she doing it to make me feel jealous ? Is she looking at other options ? I know this is normally a case of 'Guy gets jealous because of his own inner game' but the conversation seemed to be a lot more than one between two friends, lots of suggestions about texting, teasing, meeting up, 10+ messages to each other and then I know they started texting.
Help. I'm thinking I completely ignore it, act indifferent to it, but if the contact continues (might be hard to tell, I can't read her phone) then it might be worth saying something ?