How can I go through her face book

We aren't going to tell you how to invade her privacy.

If you know she's cheating on you, why would you spy and snoop? That just rubs salt in the wounds. TELL her that it hurts and you are divorcing her unless she stops and you two get counseling.

I agree... if you know that she is cheating, don't put yourself through more pain by trying to find evidence on her Facebook account. If you are just suspecting, and it may be tempting to try and find proof, the same applies. If you find out that she is, you will hurt more. If you don't find anything, you will likely still suspect anyway.

Find a quiet time and talk to her about your concerns. If she tells you about it, and you want to stay married, consider counseling. If she denies things, but you still feel strongly that she isn't being honest with you, divorce may be the answer if you feel that you can no longer believe what she tells you.

Regardless, get your concerns out in the open, discuss it, and then you can make decisions on what you want to do next.

You don't, nor is there a reason to.

You do not need it, to file for divorce, and in most cases, this type of information is not needed anyway, What do you want to do, or prove with it?

If she is cheating, file for divorce and stop wasting time