So DH and his ex were to have the parent meeting with the graduate pyschology student a few weeks ago. The day before he followed up with his ex to make sure she hadn't forgotten. She had and said "oh, we had plans to go to (a local yearly event that lasts a month)." DH told her that he was still going and did she have any of her own concerns that she wanted him to bring up because we had a lot of trouble scheduling the appointment in the first place because DH's Ex kept saying she couldn't do certain days (she doesn't work or anything). His ex said she would text him her concerns. Her text literally consisted of one thing "the only thing that really concerns me is that when he is in trouble, he sits in the middle of his room screaming and crying no one loves me or I hate this family/you" Basically describing his usual reaction when he goes into meltdown mode.
DH's meeting with the student went well. They discussed how his ex is pretty much content with SS's ADHD diagnosis and thinks all his behaviors are caused by that. They are planning for the first phase of his testing now, but they determined to only schedule them during our time with my SS since his mom already bailed on one appointment. She gave us two BASC-2 to fill out, one for DH and one for his Ex.