In reading about how the mind occasionally likes to reside in the past, I found this helpful hint, and I tried it and it worked for me, so I'd like to share it with either the ex-betrayed or the ex-waywards, when we have those negative intrusive thoughts...
I'll give you my example: yesterday my husband drove in the neighbourhod of his ex affair partner, to pickup an online grocery order. It is the grocery store where once upon a time, they both shopped in. I knew about this, and my though went into the past, to haunt me with "is he going to meet her there?" I could not shake that thought off as it chained onto, what a cheater he is, why did I take him back and on and on...I was not having a great day. 
I remembered the helpful hint of asking myself this question;"what evidence do you have today that....." I asked myself these questions: "What evidence do you have today, that your husband will meet her there?" Answer to myself, "well, no evidence whatsoever."
"What evidence do you have today that your husband is a cheater?" Another answer to myself: " There is no evidence."
I felt immediately better, no great but better. 
And maybe, just maybe this will work for you.
