Thanks PeterAndre and Grace. I have recovered my sense of humour in as much as it can only be gallows humour given the circumstances. It actually feels far less serious to me than it probably should - probably because I feel like I've emotionally insulated myself from the real shock that I've married someone entirely different from the person I believed I fell in love with.
He was my first partner. I lost my virginity to him (not all that long ago 
). It meant a big deal for me to wait which he knew. I've never, ever admitted this to anyone else but after losing my virginity he got up casually, dressed and left, saying that he was worried about his mother as she was going out that night (he lived with her). I remember putting my coat on and going to the front door thinking wtf is going on here? I had just given up something that meant so much to me and the least I expected was that he would lie next to me all night and hold me.
It honestly was the worst incident in my life. As someone who was brought up very religious, I felt physically sick and shamed that he seemed to have just viewed me as a one night stand (we had waited 5 months) to go back to his mother 
.
He honestly didn't understand why I was upset. He asked why i was upset; I was beyond tears and shouted at him not to worry people had treated me worse. He did eventually come back to stay the night after checking his mum; but he made it clear he would have preferred to be with his mum. I knew that night I had made a mistake but foolishly thought that by having sex with him I needed to validate this relationship in my own head.
Yesterday he fucked up once again. We were meant to have a family roast dinner (as we had never had once for months as he could not be arsed to either cook or help with looking after our son). He was meant to take my son for a walk so I could actually take a relaxing bath without listening out to a child's wails.
We came in from shopping and he announced that he couldn't understand a decision made by a member of my family about keeping something secret, even to close family; because he himself would never, ever choose to keep that from his mother.
I stated that I disagreed; each to their own; it was not my decision to make etc. He wanted to know why, why i believed this. How wrong this was. Why couldn't I just say to him that I agreed. He said he felt 'too tired' to take our son for a walk (ffs who has been looking after him and doing everything for the last month)
He was angry. He ranted on for 45 minutes. He was like a broken record. He was raising his voice. In front of our son - again. For 44 minutes I thought it was my fault for disagreeing with him. In the next minute I had a flash of insight and realised that this was again domestic violence / emotional abuse and yet another example of how he disrespects boundaries.
Three simple things he just couldn't do; take my son for a walk, stop talking about a topic / take a break when I request it / arguing / ranting in front of my ds.
I picked up my ds and told my husband that he had disrespected me and harmed our son. I asked him to leave the house immediately. He begged for another chance and refused to leave. I picked up my ds and said that if he refused to leave, I would instead. I picked up my keys; he tried to prevent me from leaving by blocking my way. I got out the house where he followed me to my car. I told him to leave me alone. When I got in the driver side he was opening the passenger door and trying to sit in it. I told him that he was harrassing me and I would call the police. I locked the car from the inside. He was knocking my window begging me to wind it down and speak. He then got into his car and drove off to his mothers. I then drove to my mum's because I didn't (rightly) believe that he would return to the house.
I was so angry with him. I had an alright evening with my mum even though I was very, very pissed off that he is incapable of change. He left a begging message with my mum and a very long voicemail to my phone crying, begging. That he didn't know why he did what he did. That he needed help. That he needed me to call him. That he wouldn't do it again. All BS.
Eventually I returned to the house as it was my son's bedtime. I expected him to have respected my wishes and left, but no, when I got in he was in the bath. I ordered him to leave, but it took about 45 minutes for him to finish a leisurely bath and go. He acted like nothing had happened. As if he had literally forgotten how he cried, ranted, begged my forgiveness etc.
I did more reading of psychopathy again last night. It was very insightful. Intelligent psychopaths are rare, but many people may know one. They are superficially charming but find it impossible to put themselves in another's place. They are in a sense morally bankrupt; it's not as if they are immoral; just amoral.
One website likened a psychopath to a speeding car that wreaks havoc in its wake. So much of what i read was true; yes psychopaths can love spouses and children and are hurt when they leave them. But their love is superficial and people are means to an end to them. My husband always lacked guilt - for anything. He used to tell me I worried far too much and was guilty about everything. But he never, ever seemed to have that guilty little voice in our head that we call conscience. Because in his eyes, he was never wrong, and anything that he had done could be justified.
I don't feel I married a monster. He is just a damaged individual. A lot of information suggests that psychopaths just are: they cannot help that they think differently and empathy or guilt are just alien emotions.
I saw him today; we got on tolerably well. Occasionally I see flickers of the charming and superfically caring person I thought he was, but my instincts are still screaming at me. I think I'll take their advice.