I have been following your story for a while, unsure of whether to chime in because I felt I could not add anything constructive as our situations were so different - for starters, we live in Europe, so I couldn't offer any practical help at all. But moral support I can give!
My SIL appears to be developmentally delayed, but as far as I know her only "real" diagnosis is epilepsy. Even though she's always had health insurance and full medical attention, even though my in-laws (a teacher and an engineer) have always pushed and tried, there has, as far as I know, never been a real comprehensive understanding of "what's going on" or an idea what useful therapy might look like. It appears it is just a really hard thing to get a grip on - I know my inlaws got of lot of "give her time", "stop comparing her to others", "it's all your fault for being unreasonably demanding", mainly because they tried the same kind of loving but structured perfectly ordinary middle class parenting with her that her brothers got and it was so clear that she was falling more and more behind, while her brothers turned out well-adjusted and successful. She's finished manual track high school. She even finished child care school - no one in their right mind would let her take responsibility of kids now! I am not sure how she did all of it, certainly no one ever did her homework for her, but it appears that she is not as intellectually challenged as she is emotionally and socially. As long as demands and responsibilities were very clear and mostly age-appropriate to her abilities apparently she did function adequately,
Now she appears to me like a pre-adolescent in a woman's body and that's how she lives, in a way - at her parent's house, in her old bedroom, watching a lot of TV, hanging out on facebook, interested in pop-culture geared to pre-adolescents. Her disability makes her selfish, shallow and immature. She' s manipulative and obstructive and altogether very hard to live with. She has had relationships, even one long-term relationships, but they all fail eventually as the demands placed on her increase. She is currently back in an assisted workshop program but has to be monitored, pushed, encouraged, threatened with consequences constantly to turn up on time, or turn up at all, or even phone in sick if she feels she "just doesn't feel well enough today" as she frequently does (she is not healthy of course). So while I am sure there is a lot that my inlaws could have done or could do differently no one can really blame her parents for not doing all they could, they did and do their best a middle class family can do. Sometimes there are limits in how much you can help people who resist.
Now our situation is also different in that my inlaws are still alive and mostly healthy, but the responsibility will fall on us eventually. I have pushed my DH to ask for information and records and diagnoses (whatever there is) so if we have to take over suddenly we can take over, but he's been dragging his feet (it's not like we haven't got anything else to do!) and so I have stopped (for now). However, we are both in perfect agreement that while we will always give support, we will never ever agree to live together because as he said, only half jokingly "someone will get murdered". We are hoping that she will be offered a place at an assisted living facility again (she had been offered one before by the same place she worked at then and works at now, with a hiatus of several years because she sabotaged herself, and turning that place down because she'd just saddled herself with a huge dog my inlaws didn't know what to do with, or maybe they did not really feel ready to let go and blamed it on the dog, who knows, is one of the few egregious mistakes I'd lay at my inlaws' door, actually). If not, we'll get her settled in an apartment near us, send over a cleaning woman once a week, make sure she sees her doctors (she actually loves going to doctors), try to monitor her medication and contraception as best we can (I have to admit a baby would be the ultimate nightmare) and have ner over for holidays. I hope she will have the sense to remain in the assisted workshop program this time and for good. Apart from that, it is all in the air.
I am a working mother of two myself and will soon be the mother of a special needs child myself (my third will be born with spina bifida and the level of impairment is not yet clear). While I am gaining new understanding all the time for what it means to parent a special needs child and it has made me more sure than ever that we will never ever withdraw our support, I also know that I will have to have VERY clear priorities in life. I will need to look out for myself because the mother is the lynchpin in any family - if the mother falls apart, everything falls apart. No help for anyone. Next, your marriage. If the marriage falls apart, the family falls apart - take care of your marriage. Take care of your children. And give your brother support, but not at the cost of your own life.
My SIL is in her mid-thirties. Your BIL is 30. They will not change. Lets give them the best support with what they can do. As a Christian (you specifically mentioned this, so if you don't really want to go there let me know) I ask myself "will she need help?" I know she will. I do not ask for anything back. Not even the good feeling that helping someone could give you, or knowing that there is this plane out there. Just do what you can to make life mostly safe for him, and lower your expectiations.
Edited by Tigerle - 5/29/12 at 1:52am