Whats the best way to approach this?

Right first things first let me introduce you to the situation. I met this girl online who lives abroad and well we clicked straight away. I immediately thought she was attractive but didn't say anything and just got to know her first. Within a few hours of talking she asked for my mobile number and facebook.

We've carried on talking on facebook since and i've even called her regulary around once a week. In the facebook messages she's been telling me how she's been thinking about me throughout the day and how she misses me etc.

I suggested that maybe i could save up money and come see her in the near future which she said she'd love. She keeps talking about how when she's going to parties she wishes that i was there with her. Which got me thinking that if things stayed the way they were then maybe things could get serious.

Anyway back to the problem. Recently she added a guy on facebook who was a friend of a friend that she didn't know and i assume that they've been talking and now she's saying about how she's going to see him this weekend and how she can't wait to see him with him saying the same thing back.

She never mentioned him and only told me that she was going on a holiday there.

I'd just like to know where do you think this leaves me? As still up to the other day she was saying how she missed me and wanted me to be there. (I presume she was still talking to this guy at this point) I was planning on calling her on tuesday the day after she gets back and ask her how her holiday was etc.

Is it a good idea to bring him up and ask if theres anything going on? Or should i just play it cool and not initiate any conversation and wait to see if she eventually messages me?

I really would love to see her but i'm not so sure its worth paying all that money to go see her when its clear she's maybe thinking about someone else now. Obviously this comes with a dilemma because its hard to find out whats going on and i really dont sound like complete psycho asking her all these questions and therefore scaring her off, as i know that we aren't actually together. So how would i ask this without causing this effect? I was wondering if anyone could help me out here.

Would be really grateful for your help.