Want to separate from ADHD husband...struggling...need advice!

My husband and I have been together for 8 years, have one 3 yr old son. My husband has never been diagnosed with ADHD as he has never sought out any help, doesn't think he has a problem. His father mentioned to me years ago that my husband should've been diagnosed with ADHD as a child. He also has a head injury from a bad car accident he had in his teens. All thru our relationship and marriage there has been emotional /verbal abuse. He has had numerous screaming fits, tantrums if he lost something or couldn't fix something. I've left many times only to come back and try again after all of his promises to change. He has stopped calling me names and having huge tantrums but I'm afraid the damage has been done...been called every name in the book, had things thrown at me, seen him punch holes in the wall, he's spit in my face, the list goes on. I have no trust in him and have shut down emotionally, although now a lot of that behavior has stopped, things have changed. He is now hyper focused on me, saying " I love you" ten times a day. He calls me constantly when he's at work ,he always has. I feel so smothered and yet there is always this weird, indescribable distance between us, he is always in his own world. When I try to communicate with him about my feelings or we have a disagreement he always blames me, says I just want to fight, that I'm the unhappy one, i'm too critical, I want too much ,etc. He is impossible to get through to! I feel so lonely even though we spend a lot time together because he has no friends and doesn't care to have any. He is very dependent on me for everything...emotionally and physically. The intimacy has stopped because I feel no attraction...we have a parent/child dynamic and it's a huge turn off...he pressures me all the time for sex,etc which makes me not interested even more. He has started to as me if I'm cheating on him.  He's very responsible with work and helps care for our son although he is often "tuned out" to our son's feelings.  I am at the point where I don't think I can take anymore. I feel I have totally lost myself and everything with him is so confusing. In the last year my physical health has been awful, stomach problems, severe dizziness, anxiety....been thoroughly checked out and I'm fine "physically". I feel so depleted and exhausted and fear that if I don't get out I'm just going to deteriorate and that it will affect our son. I'm very isolated , have become isolated since being with him. He makes me feel guilty for spending time with others or trying to do something I enjoy that doesn't involve him. He doesn't even really seem to know who I am as a person or seem interested in my past, or my dreams, etc. I pretty much have decided I want to separate. I'm just afraid to take the step. I just started working part time again, I've been a stay at home mom for 3 years....I feel bad for our son who will be another child with divorced parents but I also want my son to see me happy and healthy. I haven't mentioned to my husband that I think he has ADHD recently ,in the past he's gotten really mad at me when I've suggested it or seeking some help..tells me I'm crazy,etc. I want him to leave our house and let me stay with our son. He has a full time income and can afford to leave but I'm worried he is going to make it difficult, I also fear he may get really angry and react, say horrible things, I just don't trust him based on the past. Any suggestions on getting him to leave, telling him I want to separate?? I really need advice from those who have been there...I really want to get "me" back again, get out of this deep, confusing fog I've been in with him,  and make a healthy and happy life for my son and I. Please help!