The thing about separating is that I cannot imagine how devastating it might be for us not to be together all the time - either h and the kids or me and the kids.... The break up of a family is traumatic I think, even if there isn't enough love between the parents. Also it is the total unknown - who knows what might happen or whether h might go for full custody - for example - I doubt it but it's this kind of thing which makes me very frightened.
(1) Do you honestly think the children do not notice that your H hasn't spoken to you for weeks and that you don't sleep together?
(2) Has he ground you down so much that you think he would get away with accusing you of hoarding and thus be able to take the children from you? What you keep is what 99% of other women keep -- little pictures and things the children make. This man sounds so up himself that if it wasn't the artwork, etc., it would probably be your weight or the way you cook or how you parent the children that he chose to use against you.
(3) Has he ground you down so much that you cannot imagine that you, a grown up, could live on your own and manage? Hundreds of thousands of single mothers manage. Some are only teens. Please take courage. You can do this. Yes it is unknown, but do you honestly think the devil you know is better than the devil you don't know?
(4) You are not functioning well now because of the presence of your H. If he were to go or if you were to move out your life would change massively for the better. It is impossible to function well while you are being 'weirdly humiliated' as you put it. When your tormentor is gone you will feel a million times better. You are being belittled and shouted at and criticsed even when he deigns to speak to you. This is all traumatic and very stressful and the only cure is to separate. Staying together means you will remain very paralysed and fearful.
You say your sister lives up the road but she is busy. I think what you mean is that you have not really told her what your life is like and you are afraid to break the news to her. Does she have any idea what is going on? If she doesn't know, you need to tell her. Write it down if necessary.
Please put one foot in front of the other and try to trust that the direction of OUT OF THE MARRIAGE is the only way to go, and that you can do it.