i have a disabled son. my ex could never cope with it. so i got on with it.
my ex also had a breakdown left his job etc. in the end he got severely depressed and angry and attacked our son. for years i had said to him, get some help, get some counselling - but he refused - then it was too late. (he also got violent towards me so as i said, other things going on too).
i am not suggesting this will happen - but if someone finds it difficult to deal with health issues in their child, then really it makes sense to seek counselling for this - then the rest might fall into place. if you jsut carry on muddling thru then evnetually something will give and fall apart...
you need to try and get your h into counselling to deal with your child's health issues - like bereavement counselling - it is the stages of grief to go thru, to accept that you dont have the child you thought you would. it sounds like you have processed this - you accept the extra work involved etc - and he has not.
do you get any respite or help with your child's needs? if not, then you need to get some so you can spend time with your h. (if you want to!)
also Relate to work on things together - but try and find a counsellor who helps parents with children who are sick/disabled.
maybe thru a childrens hospice for example. so you can both go and especially him individually. you both need a space to express how you feel about your child's health needs and how it impacts on your lives. and come to terms with it.
it seems from reading between lines that you do not feel supported by him in dealing with your son's issues and needs. i knew that feeling well...
also your h has his own issues (mental health referred to)
further if you not getting respite/outside help so you get a break together - then it compounds it.
agree tho with making it about you and your happiness within yourself, rather than seeing it as dependent on your h.