My PTSD was present before I got married, too, and his acting out (rages, dissociation, physically leaving to work long stretches) triggered me. Most of my triggers are emotional. To my knowledge, there haven't been any affairs, but definitely have been inappropriate behavior on his part (and mine too. Revenge doesn't work, by the way.)
Learning grounding skills has helped. I'll see if I can dig up the thread the guys had going for a long time; it helped me more than female-survivor-specific sites ever did. Also, daily meditation really helps me. Sitting still and not having busy brain sets me up for a more successful day than 'get up and go'.