Poppy when are you going to get angry? Angry at how HE is making you feel, at his belittling you, at his behaviour towards your son, at his constant mind games? Get angry! How dare he treat you like this?!!
Harness this anger and let it propel you to get out of his clutches.
You have done nothing to warrant this behaviour from him. Nothing! You are a good person, loved by your children and your friends. You do not need someone like this man in your life, who drains you of your carefree spirit and happiness. He has robbed you of this time you could have had with your son before he went to uni. The bastard!
You couldn't have known that this was the man he truly is. He hid it from you until he had you firmly in his clutches, then he felt secure to unleash his true self. You have tried to make the relationship work, but it was never going to work as HE is unable to exist in any normal, healthy relationship, while you will never flourish in a relationship with him.
I suspect the reason he wanted to hear about what you said/son said regarding "mattress-gate" was because he wanted the "thrill" of the drama of it all, watching the severing of ties between mother and son, wanting you to come to "his" side and have the "us versus son" environment, taking delight in your son getting into trouble. Do not be fooled by the dear, sweet, helpful things he is doing - DIY, emailing etc - as these are things which are designed to make you see what a "good thing" you had and let slip away. You did not "come to heel" when it was expected, you were never going to be able to do enough/be enough no matter what. No one will ever be able to. He wanted his dinner early, so you had to come home sharpish to cook it - that screams control. Was he unable to work the oven? The long drawn out moving his stuff out is also designed to twist the knife in you, so he derives pleasure from your pain. He wants to see you miserable, wants you to beg him to stay, wants to see your tears, wants to hear you say you'll change/was your fault/you'll try harder, he wants to see you collapse and suffer without him - just look (and get angry) at how he treated you around the time of your biopsy. This is a horrible, manipulative, sick man.
Please, dear Poppy, understand that NONE of this was your fault. The only thing you can do now is to distance yourself from him. Stop responding to his "caring" emails as they are anything but genuine. Be factual, show no emotion with him at all because he will see any hint of emotion as a door back in to continue his little games. If he phones you at work, don't answer. Start being unavailable to him. Pack all his stuff in the spare room and shut the door. Tell him to take his stuff quickly because there is no need to keep taking bits and pieces - he's keeping a foothold in your life by doing this. And sell the house.
He has no right to treat you like this; you are not a participant in his cat-and-mouse game any more. YOU deserve to be treated with love, respect, kindness - none of these things will be forthcoming with your ex. He is the one with the problem(s), not you.