I think if you do contact her again, you’re going to have to enforce boundaries with her. But her saying you’re the only person she has left just feels like emotional blackmail to me. Have you ever told her you don’t like how she treated you, in the past? Not that she would necessarily have stopped, but her responses would have been interesting, and telling (you’d most likely have got either apologies, blame shifting to make you the issue, or denial).
If staying no contact feels safer for you, do that. She is your mother but you don’t owe her anything.