I admit I didn't read all 3 pages of prior posts so my apologies if this is a repeat.
In general my stance is, what's the point in dating someone if you're not going to trust them? This applies to Facebook, strip clubs... Basically, I'd have to literally walk in on infidelity to believe it. But some of that has to do with the fact that I choose trustworthy partners (I think).
That being said, not every woman has had positive past experiences and yours may have been cheated on before?
If she's worth it, talk to her, try to come up with something that works for both of you and work to earn her trust. If it ain't happening and you haven't done anything wrong then hit up one of the FB hoochies and let yours go. Life is short and you (probably) deserve someone who will give your relationship a chance.
But don't take my relationship advice....