As you will discover, if it's not in writing and signed you don't have a leg to stand on.
Also if you have no equity in the success of your work, why continue? It seems the others would be scared to lose you at this point. It may be time to leave if there is no equity, money or future where you are.
I work at a startup where I am the key value creator (they are heavily dependent on me) but am not a founder. A co-founder has dumped all of his responsibility onto me and is now starting another company that I have no equity in that is directly dependent on the success of my work. This doesn't really seem legal to me. Does he forfeit his equity in the original company? Do I have any legal right to his other company? Otherwise, I can just go and start company after company while hiring people who have way less equity and having them do all the work.