I cannot offer you solutions or advice but I can offer you comradery. I have Ehlers-Danlos syndrome which is in the same category as Marfans. In fact, that is what the doctors originally thought I might have. I was diagnosed a year
ago. I am 55! I am the mother of 2 adult children. So i can understand your heart ache on both sides if your problem. As a newly "disabled" person, I find that I am still grieving the person I was and planned on being the rest of my life. Someone active and strong and healthy. It's heartbreaking, people look at me and can't see my pain so it is difficult for them to believe that I am disabled. Add that to the depression created in the grieving process and you can understand why he has closed himself away. On the other hand . . .as a mother of a thirty something son and a thirty something daughter . . .I know your heart ache. My son is handsome, intelligent and creative but he is a son and doesn't always think about dear old Mom. It seems the majority of adult men tend to come home for a visit when they need something. My lives too far away. His life has been fraught with difficulties, many because of the paths he has chosen to walk. All I have been able to do for him is to promise that no matter what life brings I will always be his mother, regardless of what he is going through, as his mother I will love him unconditionally. It has taken him 36 years to understand that. I pray that your son is learning all that he can about his condition and is seeking out others with the same or similar conditions.
Just try to let go and let God carry this for you. All that you can do for him is to be there, be supportive and let him find his own way back to the light. Right now, my son checks in with me almost daily just to let me know how his day is going otherwise I might panic, he finally gets that. It took 35 years and my major melt down on the phone but he finally realized that once your a Mom you are always the Mom, and love is unconditional I don't just love him when his life is good.
My daughter used to be very close with me. She is angry with me because I have stood by my son. She picked him up dusted him off and they had a major falling out. I told them both I was neutral and would not take sides. My daughter believes that in supporting my son I took his side and stopped talking to me for quite awhile. The good news is we are talking again, providing I call her first. Even then it is a cordial phone call, not the beautiful mother-daughter bond we once shared. But still there is hope.
You and your family are in my prayers.