I feel for MB very much right now. She is such an amazing person and deserves the world. Things have been hard without adding this to the pile and I pray her an her son and all her family are strong and everything is good.
I understand reaching out to H in this situation. It is important that he be told. However it is his choice what to do with the information. She can't push t with him. This has nothing to do with DB as I see it. It has to do with a scared not and mom and a POS self absorbed human being that had no compassion or thought for anyone but himself.
History aside S was his son for 11 years and if he is going to harbour anger from the M and towards MB and push her by being a jerk that is his path and she can not change it.
We are all here praying and sending good feelings her way. She is a strong woman and will get through it. I have no doubts about that
The person that you will spend the most time with in your life is yourself, so make yourself as interesting as possible.