I'm sure a lot of people look and don't respond (like I wasn't going to) because your situation is outside of most of our comfort level.
I'm really sorry about how things shook out for you. I can't imagine not seeing your child. You do have my sympathy. But in all honesty, in reading your post, I don't feel you are ready for a relationship with your XH. And I don't know how ready you are to have your child back in your life, unless it's supervised. I hope that wasn't too harsh, but you sound very depressed and also potentially suicidal.
My suggestion: Start with yourself. You need help. Get all the help you can. Get back on your feet. Become comfortable being a single person again. Get therapy for depression. When things improve, try to get at least supervised visitation and go from there. Forget about a life with your XH. Perhaps if you become complete and healthy, he will once again see you as someone he can fully trust and be with. You have to start with baby steps. Hope that helps.
Me
In the end, it's not the years in your life that count. It's the life in your years. Abraham Lincoln
It is hard to fail, but it is worse never to have tried to succeed. Theodore Roosevelt