I'm sorry to hear about your pain, maybe what I can do is to relate my experience.
I'm a guy, not sure if it makes a difference!?
I was married for 10 years, I lied and cheated my way for a long time. 3 years before she left me, I reformed. I mentally commited myself that I would stay with and be faithful to this women. We discussed things and agreed a plan, bought the country house, I got more stable employment and broke off contact with my previous 'friends'. I believed we were building a future together.
Over 2 years later I came home one day and she told me she was divorcing me for what I had done 3 years earlier. While I'd been working in India, she'd struck up an affair with an aquantance of mine!
Without going into who might be right or wrong in this situation (I don't think it helps), I was and still am devastated after over 1 1/2 years later. I reached the ultimate low not too long ago!
It does get better day by day, month by month, but I sometimes have incredibly bad days.
I tried to understand why!
I try to do the things that used to make me happy, ski a lot (3 weeks this year), sail, do business...........
What I take from my experience is communicate, communicate, communicate. This is certainly helping me now and if I'd of done a better job in the past, it might have averted my current situation.
I'd also say that it is important to close chapters, there is no such thing as the truth, it's totally subjective. Close that door and move on with positive memories and valuable experiences and don't be hard on yourself. It's can be a killer!
Good luck!!!!!!!!!
Quentin
P.S. Every kick in the ass is another step forward.