I want to know why you left this out of the first post. This is amazingly important information. You've said the following:

I'm so fucking mad at him. He's a piece of shit and I've wasted so much money here. I am 100% done, whatever he says, he's clearly been fucking around.

He's clearly been fucking around - yet you now happen to say "Oh yeah those pictures? He totally sent one of them to me."

It sounds like he's been fucking around to please you, and you're being sucker-baited by this Ex.

You confess to the following:

• His ex randomly friended you on instagram, and called both you and him shitty names and all sorts of shit.
• THis happened conveniently when he's unable to be around you.
• You randomly go through messages in facebook and find one from her (surprise!). It'd be interesting to see if you got this message around the same time this great source of information also found your instagram and posted shit about you and him.
• She attaches 3 pictures, one of which HE SENT TO YOU
• You've talked to his friend, and he thinks it's all a lie.

So, I dunno where you stand. You dont seem to trust this guy worth anything. You however seem to trust someone who has called you and him ugly names, and has attached 3 pictures, one of which you know is true (I wonder if you could get a timestamp of when the picture was taken to confirm it's the same picture). You say that she has access to months and months of a fake relationship - why not include that in the OP as well?

What I would honestly say - is drop all investigation on this from this point on until he gets home. Own up to everything you've done (posting on the internet and saying what you did, and talking to his friend and him saying what he did) and get to the bottom of it.