It can be really hard to encourage someone to seek help when they're not intrinsically motivated to do so. If he doesn't see a benefit in it, he's not likely to pursue it. He may have his own biases about it or anxieties which also keep him from wanting to do it. The idea of the ultimatum that was given to him may have been the only thing that would get him in the door right now.

I would say there are a couple of good books that you can read - "When Someone You Love Has a Mental Illness" and "I'm Not Sick and I Don't Need Help." Both of these are available on Amazon.

I'd also suggest going to NAMI (National Alliance on Mental Illness) meetings. It's like the Al-Anon of mental health, for family and friends of those with mental illness. Often times you can learn a lot from other families who have dealt with similar challenges and frustrations.

Bottom line, you have to decide what limits you're going to set for yourself and what you want. It's very likely that he will not change and will refuse to get help as he doesn't see a benefit to it. You can try to educate him and challenge his resistance, but sometimes people have to come to that choice on their own. Therapy only works if you're engaged.

Sorry to hear it's been such a long struggle. Best of luck.