I know I need to stop dwelling in the past and searching for answers that are not there.
I think it is important that you do know that it is important to stop dwelling in the past AND that you know that the answers do not exist. Those are essential steps if you are to get beyond the devastation of what you have experienced.
It is very important that you not repress the pain of what you have experienced as it will continue to haunt you if you do. You really must process it - but what in the world does that mean and how on earth can you do that? The truth is that there are many ways. I am very familiar with a few and will share them with you.
How will you know if any of these suggestions are for you? If they resonate with you - at all. If they sound interesting and you are drawn to them, are curious about them. If not - then keep looking. Use the intention/manifest technique to draw healing and relief/release to you.
The primary technique I use is a form of CBT that I learned in a very interested, scientifically based book by a psychiatrist Dr. Jeffry M. Schwartz, who focuses on OCD. In his book The Mind and The Brain, Schwartz describes a 4 step process which OCD patients can use to stop their obsessive thoughts. My experience in grieving has been that the thoughts take on an obsessive quality - they seem to have me rather than me having them.
Schwartz' Four Steps are outlined in detail in the website here:
Dr. Jeffrey Schwartz' Four Steps - Westwood Institute for Anxiety Disorders. If this appeals to you I suggest that every time you read OCD in the 4 Steps that you substitute that phrase for the word "grief" or "grieving". You are grieving a significant loss but your situation is more complicated than simple loss b/c you have been betrayed and there are multitude of complicating aspects that contort and intertwine in and amongst the grieving. I suspect you wonder what part of the past 10 years of your relationship were real or honest and what parts were not. Such a betrayal also sets you up to wonder how you will know whether you can trust someone in the future or if you CAN trust someone again. That is all by itself a painful question and points to yet another loss - the loss of trust is in itself a significant loss.
There is yet another approach that I use which I find to be very powerful though difficult but it is perhaps even more controversial and this step cannot, should not be used too early in the mourning process. You must be "out of the hospital" so to speak. This process is forgiveness. It really takes a book to describe what I mean by this and why I say it is so valuable. But I am going to cut to the chase. By forgive - I do not mean let her off the hook and just say, "oh it is all ok what you have done and I don't care anymore." Rather what I mean by forgiveness is a process that allows you to let go of your anger and resentment. You will never heal as long as you hold on to those. Google "Steps to forgiveness" and you will find many suggestions. Here is one that if fairly good. You may want to ignore Steps 2 & 3.
SGN - P. Baute: FORGIVENESS: 14 STEPS.
I have given you a lot of material to cover. Some, all or none of it may be helpful or interesting to you but perhaps it will be a place to launch off a valuable journey toward healing and letting go both of her and of the pain she caused. Hope your journey takes you to a safe harbour. - WK