Hey there, sorry things are going badly with the L! that's awful! hope he doesn't drop out.
About IL's same here, MIL (the surviving parent) has told H how he had surpassed his dad (H hated his dad who was bipolar and abusive to them). H did tell me on occasions how her banter didnt' help and he just stopped talking to her. I told MIL that we had to let him go, if he had to fall on his face to learn so bit it, that if his life was going to be heck with ow, then let it be, that that was the only way he was going to learn. Eventually MIL got it, and even on one occasion H was calling me she told me not to pick up the phone, to let him squirm, to let him hang.
Perhaps talk to your MIL and explain her that no sense can be talked into him, that he had to decide by himself what was right, and that that may not happen any time soon.
Be not afraid...I will repay you for the years the locusts have eaten Joel2
30something 2kids survivor of S, MLC, A, D I have peace in my heart, at last.