I am really sorry to hear of your loss and worse still, to keep continuing to hear how your husband (and sister and in-laws) are not supporting you at all. My heart breaks for you - you are so young and have so much going for you, yet you are in a difficult situation and there are no easy answers.
I am so, so happy that you are getting counseling with your husband - I believe it is absolutely imperative for you to do that to get a handle on where things are not good in your relationship. From what you have shared here, and several others are of the same opinion - that your husband could have Narcissistic Personality Disorder (NPD) and that is very difficult to treat. Just be aware that if you do go to counseling together, he is likely to turn everything around back on you, manipulate the counselor into seeing him as the blameless 'good guy' (they are VERY good at that) and will come out of it blaming you for everything. So if that happens, see the counselor on your own and be very firm about the way his behaviour made you feel, and how unacceptable it was, before trying to do joint counseling again.
Right now, you have a lot to process - this has been something that has shone a very strong light on your marriage, and that is a good thing. Better to find out now, than down the track when you are older and possibly have a family. Even after my eyes were opened, it took me a further eighteen months to leave my NPD partner, so I understand that these things can't be rushed and you have to go through the whole process of evaluating the marriage, and for most women, we try everything possible before we go. I know with my relationship, I could walk away knowing I had done my very best, so I had absolutely no regrets whatsoever. We all get to that point in different ways and in different time frames. At least you are aware now, and can more forward with that knowledge and assess the next steps.
With regards to your business- it is a dream and we should never give up on our dreams - but the timing may not be right now. Whatever you have done thus far will not go to waste. If you do shelve it for a couple of years, you will have all that knowledge and experience behind you when you are ready to launch again. It's not a failure, the dream may just need some time to develop in a different way at a different point in your life - so please don't be black and white about it - if it's not flowing, then it may not be right, for right now.
Just before I finish my essay (lol) I do want to agree with @Daisy Duck - when I started bleeding with my last miscarriage, my husband rushed home from work to be with me, he comforted me, cooked for me, cried with me, held me and was so incredibly kind, gentle, loving and caring. Then he took a day off work to be with me for the D&C and afterwards we sat on the beach and talked and cried some more, then had a lovely lunch out and he took care of me for the days after when I was feeling raw and vulnerable. No matter whether your baby was wanted or not, you are still going through a very difficult experience and deserve, love, support and kindness. I have not seen one thing from you that shows any of these traits in your husband and that is tragic...
You are a strong, good-hearted woman with an amazing life ahead of her - believe in yourself and gather around you people who are on your side (even if it is a paid counselor!) - those who champion you, see your worth and love you for it. And spend as little time as possible with those who don't. They are not worth the effort.
Much love to you,