I'm interested to hear the outcome as I went through a similiar situation and I am doubting my decision.
How are things with A? How have you been able to work on the communication aspects of your relationship (assuming it is still there)?
How are things with your secondary? Did she stand by you? My secondary, J nearly left me when I had my scare with K. However now he is a primary . He stood by me when I was at my lowest which I know takes a very strong person. I feel guilty for it though because now he is having trust issues himself. I maintained my relationship with K but he is trying to make me distance myself from J since J no longer trusts him. I have my fears that K will do it again (much like in your example with A) and I cant help but feel disconnected to him at this point.
It has been a struggle the past 9 months working through it but I think I am finally seeing the clearing in the woods.
I wish you the best.