Sigh. The PMS certainly does make it harder to pull out of the funk. And I'm sorry the brick hits keep coming. I think you're right--the poison has to come out. You've had to swallow a lot of it. Once it's out, I know you won't let it come back and do more damage.
Do you have any strategy for changing your focus? When I was bombarded with thoughts of H's betrayals, I would chant over and over: I enjoy a happy, fulfilling M to a loving, faithful, worthy man. (Notice there are no names there--if H wants to be that man, great. If not, someone else will be.)