BM is trying to blackmail DH now
After all the accusations and nasty comments BM made, DH told BM that SD also says things about her and her household that concern DH. Well now BM is in panic mood and avoided answering DH's question on calling SD, so after 3 more lengthy paragraphs of harassment from BM, all DH did was re-ask about calling SD and BM responded that she wasn't going to discuss him calling SD until he shared specifics of what issues SD has said about her and her household.
So basically BM is trying to blackmail DH into revealing what SD has said in confidence and hold his contact with SD hostage until he does so. Uh, yeah not going to happen. DH called her out and asked if she's denying his rights to access to SD and blackmailing him. Waiting to see the response but we aren't going to share that info, at most DH will say he shared those issues with the therapist who is a third party who SD might be the most honest with since she's not trying to please either parent in talks with the therapist especially since last time DH brought something up SD said BM called her a pretty great liar.