Sigh...I went back and read your previous posts about her. Back then, it seemed clear that she didn't want you to contact her and you wanted to win her back.
Now reading your current posts, I have a question---Why oh why did you want her back?
You say that you're snooping on her phone and her FB page. I assume that she gave you her FB password or is it that she has her privacy settings on low? If it is the latter, then it is out there for everyone to see. If it is the former, then you're right---you shouldn't be snooping.
Yet...you say you're snooping to "protect" yourself. You also say that she's a pathological liar. You also say that she loves you. It sounds to me like she's incapable of loving anyone.
It's very, very clear that she enjoys playing head games with you----and it's also clear that you keep taking the bait.
Why do you even want to be with this woman? She treats you like dirt and cheats on you? Don't you think that you deserve better?
If you feel that you can't trust someone and feel that you have to snoop, then the relationship isn't worth continuing.
You wanted advice so here it is --- DUMP HER ASAP!
If you really can't stay away from her, then maybe it's time for some counseling to find out why you keep going back to her. I think you need to do this because even if you don't go back to her, you most likely will end up in a similar relationship. You will just keep going round and round doing the same old dance.
Oh---and you ask who is at fault here---Both of you are at fault. She is at fault for treating you poorly and playing head games. You are at fault for taking her back and putting up with all the BS and drama.