Could you clarify a few things?
How old is Evan? Is he in medical school? Is he financially independent (has a job, scholarships, etc) or does he have no money or income of his own?
Are you serious when you say you took Evan's car back, and you refuse to drive him to school or work, and you don't let him watch tv?
When you say "takes care of me", do you mean you require physical assistance with daily activities due to illness or disability, or do you mean that he's a supportive son who makes you tea and chats with you?
Your talking to professionals is not going to resolve your husband's and Evan's clashes of personality. It's sad that your husband can't appreciate Evan for who he is, and it's sad that Evan hates his dad and spends his days crying.
But if Evan is an adult, who can handle the rigors of medical school and hold down a job and has a girlfriend, let him have a life. If you need a nurse or personal assistant due to medical issues, ask your doctor about what to do.
OCD is a serious mental disorder, but being anal retentive isn't the same as having a disorder. By definition, someone with OCD is compulsively persistent in certain behaviors, and someone who is anal retentive takes pleasure in having all the cans in the cupboards alphabetically organized, and all the pens organized by ink color. It's a sense of pride in maintaining order and neatness. OCD is something altogether different.
Help your son get a life of his own, and pursue his medical degree. Encourage him to move on.