I couldn’t read your post and run. Huge hugs to you, it sounds incredibly hard and you are stronger than you know, you have already been through so much.
I can’t see that reaching out for help would result in your son being taken off you, that makes no sense for him or for you?
Please speak with someone, Samaritans, or any of the other people mentioned. Also if you reach breaking point or cannot speak with anyone else please phone 999. I had to do this once when a friend was suicidal and it was literally a life saver. They are happy to help and will take you somewhere where you will be safe.
You need real life help to help you see that things will get better, step by step, that you do have the strength to keep going. That if anything happens to you, the world will be a worse place for many people. They say that with suicide, although your pain may stop, the pain doesn’t go away but it ripples out to many people, family and friends, who are left to make sense of the decision and wonder what they could have done to intervene. Much better instead to reach out for support to help you deal with your suffering from whoever is able to give it - family, neighbours, Samaritans, whoever, I would even go to a church community (I’m not religious!). People will be there to help you if you reach out. I imagine it would also be far better for your son to be looked after by someone else temporarily while you recover your strength than for him to lose you.
This time will pass and you will look back and be so glad that you made it through, for yourself and your DS.
Also don’t forget to talk to yourself as you would to a good friend. What would someone who loves you say to you in this moment?
Be kind to yourself, OP, you are living through a brutal time but things will get better. Don’t give up. Sending love and strength xxx