[Terminal Est]

I see your dilemma.

Know that those who come to you heralding changes within themselves, usually pertaining to what has gone wrong to begin with, is never true. they never change, and people can never really change. And this you must accept, because you fell in love or were attracted to somebody because of something-for what they are, not what they might have the potential to be.

What is important is how you feel about it, and how you think you would feel about having her back. But there are two sides to a relationship, and although you've not elaborated so much, I am getting the impression that you are wanting to give her a chance based upon what you feel-what about her? Do you want to make HER happy?
She cheated on you indeed-but did she tell you why? Perhaps this can never be justified, however something still drove her to do as such.
Of course, I would suggest that you do as you seem to have been doing-keep being a realist.

If you consider and envision all these things going wrong or keep feeling anxieties and the like, you are better off leaving her for good.

Stupid mistakes and experiences create knowledge-but it does not always have to be with the same person.

But I must stress, the situation and what you decide to do with it is relevant to your own feelings, and the consideration of the feelings for the other in the relationship.