Thanks for writing back Broken. I understand what you are saying. When you say you know she be coming home to you....that is a pretty low bar. Set it higher.
Don't share her. Consider yourself worth her loyalty. Boundaries are so very important.
I really am concerned for you in that you fear confronting her when she is doing wrong to you. That is very, very unhealthy. And it really does her no favor either. She needs to develop as a person. She needs to be led into virtue....not being a lier and deceiver. Not being a cheater. You not confronting her is enabling her to continue those behaviors.
You might want to look up codependence. I understand, we all need connection. That is built into us. But we really are designed for secure and loyal intimate connections. Not ones where you never know of your love is out loving another.
Again, please hold yourself in higher regard. Trust me, you DO NOT NEED HER, as much as you think you do. If you got healthy, and set your foundation on something more reliable, namely God first, then your inherent value a human based on your relationship to God....then you could start allowing yourself to chose and build a secure, exclusive, intimate relationship.
The more and longer you let her abuse you, the worse you will feel about yourself, and the smaller you will be in her estimation....even if she does not speak that. If you start holding yourself in higher value, worthy of respect and loyalty....then she must start seeing you that way....or she will have to move on to someone else she can control and abuse.
Do you really want to be with someone who will not show you respect and loyalty?
Please don't take this as offered with ill will. I care for you. I don't want to see you end up as some safety net and wipping boy for a women who really only cares for her own ego and validation.