Hello Iam. First, I'm sorry you are here.
But I'm glad to hear that your questions are about YOU and not your WS or even your marriage. Focusing on you is the right move.
Let me say that getting together so young and sharing that many years of life builds a pretty strong bond. We are wired to bond to other humans for survival. Losing that, no matter how "bad" it might have been, causes a genuine biological response: usually pain and panic. So know that you're feelings are biologically driven. Perfectly normal. The trick, in part, is to start letting your rational mind make the decisions. Some steps you might take:
Self care - you're going to need to soothe that lizard brain to quiet it a bit. Comfort yourself with good self care and doing pleasurable things for yourself. Some also find meditation, exercise and therapy as helpful tools to deal with the anxiety.
See a lawyer - not to file but to start to understand what your financial life might look like if you end the marriage. Knowledge is power. This is a first step that doesn't have to go anywhere but many people feel empowered by doing it. Often what we fear is simply the unknown. Find out.
Employment - are you in a position to find and take a job? I can't tell if you're "working beside" your husband means you are his full time employee. Either way, you need some independence and this is a great first step. It doesn't have to be major - go work at a coffee shop or book store or Walmart. It doesn't matter. An identity out of your home that also gives you some financial independence will boost your self-esteem.
These are first steps but ones that are aimed at your healing and your independence. I promise you once you start to feel stronger, it gets easier.