I am appalled at the thought of your H putting your D3 in bed with him and OW. This is totally unacceptable. I think I would very strongly suggest that this not happen and ask H why D3 would say this if it is not true. IMO this should be confronted and not let slide. H should know just how unacceptable this is.
You are a much stronger person than I am. I am afraid I would reacted from emotion and not given myself time to find the best way to approach it. I am not suggesting you blast your H but I do suggest that you be as firm as possible with this boundary.
Everything happens for a reason, maybe Dad needs to find that it isn't better out there, he needs to realize how good he had it here. Maybe he will find God and that is the most important thing when he finds Him he will know he is supposed to come home.
