Feeling hopeless, stressed and angry

I'm new to posting here, although I was lucky to find this site almost a year ago. I guess I'm finally getting the courage to share my feelings and experience. I see I'm not alone in this. My husband has what I believe to be undiagnosed ADHD. He exhibits all of the symptoms and so many posts that I have read look like something that I would have posted myself, almost verbatim. I've been married for 6 years now and we have a beautiful little girl who is now 4.  We dated for 8 years before getting married and everything was perfect. We never argued. Shortly after we had a child, something changed. It's like he detached himself. I gave up my career about three years ago to be a SAHM because I had very little support from hubby around the home and with caring for our daughter, especially when she would get sick (daycare). I worked over an hour away and long days. He is a very loving father and husband, but he just doesn't seem to get it. He doesn't know his "role" (it always seems like he's acting, not really understanding). I have to spell everything out for him and when he still doesn't get it, I'm sending him mixed signals.  It is impossible to approach him with anything that's not praise of him and he never takes any responsibility for his actions. He is always on the defensive. I have tried several approaches to try to get him to see a therapist or something to make sense of things, but he gets so angry upon mention of it. This is the person who used to joke about "for sure i would have been diagnosed with ADHD as a child, if they knew about it back then". I've  given him books to read (Orlov's and Hallowell's...to mention a few) and they wind up either going missing or buried somewhere in the trunk of his car. He is in total denial and is one of those individuals who feels that he is overly gifted and is just happy-go-lucky with life.  He thinks that he knows everything without researching it or reading about it, just because others know about it. When you try to explain things to him, he talks over you and challenges everything. I discovered our daughter has a nut allergy and he has yet to read the books I've purchased or look it up online. He doesn't even read labels before giving her unknown foods and understanding how to correctly use an epipen....forget about it. He thinks because I know he knows. He once administered an inhaling solution (for asthma) to be used with a nebulizer machine ORALLY to our daughter when she was 7 months old because he didn't bother to read the prescription leaflet or just look at the pharmacy label! All of this after I told him do not even bother to fill the prescription because I knew he would not read the instructions thoroughly. I spoke with both, the doctor and the pharmacist (I panicked) and they both said they asked him if he knew how to administer the meds, he replied " yes...my wife knows". I had no idea what a nebulizer was, nor did we have one! Somehow in his mind, this was my fault because "he was under the impression that the medicine was like another one she had in the past". Thank goodness nothing happened, it was just considered a concentrated dose. But I guess that's what I get for expecting him to follow instructions (take her to the Dr. and then go straight home to meet up with my mom....do not fill the Rx). How can I depend on him to co-parent when I am the only one looking out for our child's safety. I'm the only one trying to educate myself on how to better raise a child and he just wings it and hopes it all turns out okay. I am always angry and frustrated. I try to be happy, but there's always something that triggers my frustration with him to the point where I am now losing sleep and almost hostile, at times, which I don't like because that impacts the entire family. I hate to yell at my daughter, because I'm angry with him.  I do all of the work around the house and maintain any business affairs, he just goes to work and comes home. He's convinced himself that the company he works for will crumble and fall, if it wasn't for him. No one else seems to see the dysfunction that I am all too familiar with. He's become "addicted" to work. He works Mon - Sat and will work all day, only to get off and hop in a car to drive hours to a job site to work overnight. He never takes time off, not during the summer, or if he is sick, if I'm sick, to give me a break, nothing. But, he'll come in in the evening and want to take a 4 year old out for ice cream at 8pm!?  Then he complains that she should go to bed earlier. Everything is my fault. We went on our first family vacation this past spring and it would have been a nightmare if I didn't have the foresight to invite my mom along for help and start packing a month in advance. He basically works up until the night before, packs his stuff the day of and we're off. He has nothing else to do to prepare, but then in the morning he's grabbing bags and loading the car, in a hurry, without making sure that its okay to do so. I'm trying to take a shower,feed my daughter breakfast, make sure we have everything and lock up the house, while he stands outside looking at what the neighbors are doing.  His left hand is an IPad and his right is a laptop. The TV and video games are always going. When he is home, he creates this weird energy that creates anxiety and is now affecting our daughter. I'm beginning to wonder if she too may possibly have something going on, but it seems like she feeds off of his energy, for the most part. The two of them together on the weekend is a recipe for disaster. When he's not around or out of town, it's so peaceful. I wish I could just go away or send him away for a while, just to be able to think clearly. At this point, he is just a paycheck. He doesn't appear to care, won't go to the doctor, hasn't seen a dentist in over a decade (yuck), constantly forgets or loses things, half does or messes up things,etc. But goodness forbid if I say "hey you forgot to close the freezer or the garage door", he then resents my existence and the fact that I called him out is cause for argument. There's no support (emotional or otherwise),no intimacy, no communication, no apologies or acceptance of fault and no help with our child or around the house. He's clueless to how his actions have affected us and is quick to tell me that I like to be miserable. He's found it easier to blame my anger and frustration on everything from baby blues, post-partum depression, cabin fever to bipolar disorder, but won't accept his role in any of it. I don't want to just walk away and break up our home, but I don't know what else to do. I can't force him to go get help and me going for help is not going to fix his issues.  I feel like I need therapy after dealing with him, if i don't get some form of help things will just continue to get worse, which frightens me, being that I am the one primarily responsible for our daughter. Thank you for letting me get this off of my heart. I believe that the guilt and shame that I have held in all this time has become toxic and is turning me into someone that I don't want to be. It's been eating away at me to the point where I have almost lost myself completely and have lost so much  of the valuable time that I should be cherishing with my little one. It's time for a change.