I am separated from and in a custody battle with a narcissist, who may or may not be a sociopath. I don't think he's a psychopath, but sometimes it's hard to tell.
There are a lot of really good videos on YouTube about this. Search YouTube for "Narcissism", "Narcissistic Personality Disorder", "Narcissistic abuse", and "Narcissistic Abuse Syndrome". As well as searching for YouTube videos on things like "relationships with sociopaths" etc. , but DO NOT TELL YOUR HUSBAND YOUR SUSPICIONS OR LET HIM KNOW THAT YOU ARE WATCHING THESE VIDEOS.
Apparently, all sociopaths and psychopaths are narcissists, but not all narcissists are sociopaths or psychopaths. The main differences, really, are how much awareness they have of how their behaviour and attitudes affect others, and whether they treat people the way they do, just because they are selfish and arrogant, or whether they do it because they are selfish and arrogant and also enjoy making other people suffer.
For all three, though, it is very difficult to handle it, and it can literally destroy your mental health, and take a long time to recover. If you are married to someone with any of these personality disorders, it will become obvious to you after watching two or three videos, and the more you watch, the more certain you will become, either way. If you are still not sure, after you've watched several videos and given yourself time to process what you've learnt, search for videos on "covert narcissism" and variations thereof.
You may be quite shocked by what you learn and you may not want to believe it at first, but if you are married to a sociopath, you will likely find some validation for the emotions you've been having, and likely one of your first thoughts will be, "Wow! So I'm not crazy, after all." You will likely feel a combination of fear and relief.
If your husband is not a sociopath or narcissist, you may still have trouble believing what you learn, and you will probably feel a lot of relief, but the videos will not resonate with you or seem to touch the core of your being, and you will probably not experience fear with the relief. The feelings of disbelief, I would imagine, would be more from not believing that anyone could be so cruel and heartless, and the relief will be more "Thank goodness I'm not married to someone like that" (this is how I felt when I watched videos about being married to a psychopath), and maybe "ok, so there might be hope for my marriage after all" (I never felt this way, but began to understand why none of the counselling and marriage courses we went to seemed to make any lasting difference).
Whereas if your husband does have a personality disorder, or even strong traits of one, the disbelief will be more like, "how can this be? Is this really happening to me?" and the relief will be more like, "well, at least I know what I'm dealing with, now, and there may be hope for recovering my sanity, and well-being" (this is how I felt after watching the videos about narcissists and, to some extent, sociopaths).
When I was still confused about what was going on, a book I found very helpful was one called, "too good to leave, too bad to stay." I can't remember who the author is, but it helped me to look more objectively at my situation, and get past the idea that I had to figure out whether my marriage was "good" or "bad", and realize (and accept) that it was both, not either or.
Anyways, go watch some videos. It should definitely help to figure out whether they apply to your marriage or not. If they do, make sure to find some support for yourself. I can give you some ideas for how to do that, if you want. You may have already figured out what's going on, since I see you posted this several months ago, but if you are still struggling, I hope this helps. Let me know how things go, and if you want to chat/message any more.
And now, I have to go write the document for my lawyer, to try and refute the lies that my husband used to take custody of our daughter away from me, that I've been procrastinating on writing, by answering questions, here.