Infidelity is hard, serial infidelity is much worse. I'm sorry for what you're going through but glad you have found a community where many of us have been through similar experiences, and we can learn from each other.
When you said that she's gone through episodes in the past, what did you mean? Can you elaborate?
Do the two of you have any kids?
The only real way that I know of to handle adultery is by defining and maintaining a boundary that you are comfortable with. Some people can accept infidelity in their relationship and have a less strict boundary, such as all sex outside of the relationship has to include protection. Others are very firm on the line of neither party having a physically intimate relationship with a third-party and any crossing of that line will be the end of the relationship. Each relationship is unique, so you'll have to decide where you stand on this issue and where your boundary is.
I would suggest that you continue to read the posts, read the articles contained on this web site, and some of the recommended books. I know your life is difficult now, but knowledge will help you make the right decisions. We'll help and support you however we can.
Keep us posted!