First, I would like to say that you are to be commended for seeking help here. Many people would become so frustrated with your situation, they would give up or look for an easy way out.
I found your post in the caretaker section. I am a caretaker of a (young adult) daughter w/cidp, and so cannot answer issues directly related to gbs, but you will find support and understanding here from myself and others as you learn to deal with this new responsibility you have inherited.
A part of the conflict you expressed is fear of relapse – this could happen, but as others have noted, the relapse rate of gbs is very low. From your description of Bil’s daily habits (choices), I would think he has a MUCH GREATER risk of other serious repercussions: heart attack, high blood pressure, stroke, diabetes . . . you get the idea. Bil makes these personal choices (smoking 3 packs a day?!) and you should not feel guilty for his detremental actions. On the other hand, his self-defeating actions could be an indicator of depression. You didn’t mention if this has been considered, but it is often associated with serious/chronic illnesses. That may be an avenue for you and your husband to look into.
Have you thought of inquiring either your health care provider, or a social security case worker for help with family counseling? This could help you and any other family members to deal constructively with the situation. If possible, have a family meeting, with the aim of bringing everyone involved together in a conversation that sets some goals towards a healthy emotional relationship. If Bil refuses to participate, let him know that you need this, and will look into counseling services without him. In time, he may realize the benefits of looking beyound his own needs. I know that sounds harsh, but respect works both ways, and despite the disabilities he is having to deal with, that would be a goal worth persuing. Counseling may have an added benefit of opening doors to past interests Bil had before gbs changed his course in life. He may not be able to fulfill his dream the way he envisioned it, but even volunteering in some small way in a field that interests him can be a big boost to morale.
I could go on, but I’m afraid I’m beginning to ramble. Please invite Bil to become a part of the forum – there is so much love and support here, he has no choice but to benefit from the care and understanding. Please return, yourself, as often as necessary to let us know how things are going.