My husband's family dismisses anything happening to him, but they want him to help them and caretake their feelings

Long story short, husband was raised by an NMom and enabler father. He is the scapegoat/black sheep and his younger brother is GC. His parents talk to and help his brother constantly, but largely ignore my husband and downplay anything going on with him. However, he is the "capable one" (mostly because of being neglecting and doing everything on his own), so they often tag him to help them with anything practical or hard.

Recently, he was diagnosed with a progress, degenerative neurological disorder that makes things very hard for him day to day, and it's getting worse. When he told his parents, NMom told him that now his brother would be the last to know, and had he thought about how his brother will feel now? She then went ahead and spent hours talking to his brother and other extended family members about his disease and doing "research" and has never asked him how he's felt at all.

When he tried to speak to both his parents about how much this hurt him, they told him it was actually his fault because he doesn't call them (while younger brother does), he doesn't tell them anything, and he doesn't call his brother enough, so they HAD to make him think about his brother because he doesn't think about his brother enough on his own. FIL basically shouted him down, backed up MIL 100 percent, and said "how dare you upset your mother!" Of course, nothing changed except that his mother doesn't want to talk to him at all now (we are not chasing, good riddance), and she only contacts him through FIL when she wants to see his kids or she needs him to show up on holidays for her pictures.

Now, MIL and FIL had some bad issues with their house, and MIL is leaving FIL alone to handle it all, all while she just shares a million pictures on social media and talks to her younger son and extended family on the phone for hours about it. He is calling my husband in complete upset and asking my husband to help him and help soothe his feelings because he's in distress and she's refusing to listen to him or help him with anything. Which is 100 percent the things she was doing to him, that he tried to speak to them about, and they basically told him he's a terrible person and borderline insane for saying it.

Has anyone else had this happen, where they want comfort and support from you but provide 0 back? And how can the enabler want support for the very behaviors that he's helping to support again others?