My mother had, or is having, an affair with a man who is a very close family friend. I've grown up around him, and my family even shares property with him and his family( he is also married). I suspected the affair for a long time, but it was confirmed to me one night when they both got increadibly intoxicated, and (very obviously) fooled around under the table at a restaurant with my father and I sitting right next to them. My mother is somewhat of an alcoholic, and blamed it on having too much alcohol that night as an excuse to my dad, however through a bit of snooping I'm quite certain it was not an isolated incident, and it still continues. My mom still gets drunk multiple times a week with this man and the rest of their group of friends, and my dad is forced to tag along to make sure she doesn't do anything bad again, but it hurts him every time. I don't think he knows it's still happening. I don't know quite what to do.