I knew this day would come, DH has been divorced previously and has two children from that marriage, within a year after his divorce from BM1 he had full custody of his two sons and she was not involved at all, she suffers from severe mental illness which presented in adulthood. With that being said he never had to "share" his children with another father figure. BM2 (our current HCBM) had 3 children from previous relationships when they got together, and then together they had one, SS11. So he has been a step-dad, but he has never had to deal with another man in his children's lives.

Fast forward to now.....I have been in the picture for a year now, and we have been married about 6 weeks, we have 50/50 custody. As I stated BM is HC with lots of Narcissistic traits, there is no coparenting, we are lucky to parallel parent with her at best. In the beginning she didn't want SS anywhere near me, she even filed a restraining order against DH and included SS when we first moved in together (she never showed up to court), she would tell SS that he didn't have to listen to me, and that she was his only mommy. Typical HCBM stuff. In court the mediator and judge told her that she has no say over what happens at our house or who DH chooses to be with. 

While BM is definitely HC, she also had some valid points, and I would voice that to DH when they would arise, and I often told him that he did not understand because he has never been in the position of sharing a child, I have, and it is hard in the beginning (or atleast is was for me). He just thought that she should trust his judgment as SS father, and she should be grateful that SS had me as a SM. Nice sentiments but not always practical.

Well BM now has a serious BF, I do not think they actually live together but he is there all the time and is part of SS life. She has had many BF's during the marriage and since the divorce, lol, but this is the first one she has introduced to SS. A couple weeks ago SS called DH and told him he was working on moms washing machine with new BF, I could see that it upset DH, but he said he was fine. Well this morning he tells me that he thinks BF is going to attend the end of the year picnic at SS school and he doesn't like it. So I remind him that just like she didn't like when SS and I did things together, he might not like it but he has no say, that he has to trust her choices just like he wanted her to trust his. Unless we have proof otherwise. He didn't like what I had to say, and went to work pissy.

Any advice?