So far it has been a month since I went completely dark and he hasn't responded or reached out. I still think its the best thing to do for now. His anger and resentment towards me is overwhelming and abusive, so I believe staying as dark as possible for as long as possible is what I need to do for now. Until he is able to resolve, let go/forgive, or accept his role then there is not foundation or relationship that would be healthy for either of us.
I am hoping that his family will try to encourage him to seek help, but there are VERY dysfunctional (FIL is addicted to pills, BIL is addicted to sex, and MIL is probably the most severe co-dependent I have ever met) as well and I don't see them doing anything but enabling him further. A fried told me that there was a picture posted on FB of the OW and she looked like she was on drugs or under the influence, which is frightening but I can't go there emotionally.