Oh gosh, I'm so sorry you are dealing with the fallout from all this.

Your son is an adult, he is making his own decisions - that is an essential part of growing up, and one that many of us parents struggle to cope with. It sounds like your H hasn't quite cut those strings and he is struggling to let go.

Hope while all this is going on you can find yourself a safe space away from the disharmony and conflict, take good care.