Disrespect from family

For the past year its been up and down like a yoyo .
found out I have fibromyalgia after 10 years of on going pain and other issues.
Tried to explain to my family the reasons for me not being able to do the tasks
I used to due to the pain I go through on a daily basis.
Thinking since they were all adults now they would understand .
Was I fooled my youngest which is 19 has been very cooperative however the
other 2 its been a struggle there 30 and 21 .
I could really handle some advice as specially with the 30 year old .
He holds a major grudge against me for quite some time .
I have bent over backwards for him all his life until he got into drugs
and became very selfish. It seems like the older he gets the worse he treats
everyone including his own family
I know he is not happy and hasn't been for along time but he can only fix that
I cant and he expects me to perform miracles I listen give advise however he wont take it
He would rather argue and treat everyone like shit including his son that is 9 years old
we all get called some pretty nasty names just for saying the word sorry no I cant his behaviour
has a huge impact on his son but his son is medicated for anger and a few other issues that is caused
by that kind of behaviour . I try to take his son as often as I can because of that but now that im limited I cant as often as I used to so now im a looser,bitch and a few other names he has even told me im dead to him so I gave up trying hope its not a mistake I do love him just cant take the abuse he hands out The C.A.S has been notified several times about the yelling and screaming constantly and does absolutely nothing about it blames it all on the child because of his issues caused by the parents
The bottom line is he is extremely jelouse over his younger brothers and his son
My 21 year old is slowly coming around he has started to talk respectful to me now but still refuses to help around the house unless I pay him he says the same thing as his dad my expectation are to high not sure how they think that all I expect is for them to clean up there own messes by putting there garbage in the garbage and do dishes theres only 3 people that lives here now
I don't expect them to clean up after the animals or vacume anything like that
So if you read this and give me some advise I would appreciate it or you are going through the same thing please reply or comment below this behaviour has taken a real tole on me