Thought it was only me who had a mum like this 
My DM is well meaning (I think) but isnt able to cope with and talk about emotional stuff very well so its almost as if she goes into attack mode, until your self esteem is on the floor. When I was going through issues with my ExH, she made me want to leap from the nearest window. Seriously.
Whatnext074 Im so sorry you're still feeling down. I would try not to worry too much about your DS, he sounds lovely and supportive, he's just having a blip as he is worried about you. Tough love wont work for you at this time but some of the things he says are pretty logical, arent they (not the bits your DM is influencing him to say). He is your son, he needs you. As his mother, its also worrying for him to see the hurt your're going through.
Your DH didnt make you, dont let him break you. Please. Not this, over a man. You have your life, and a lovely DS etc. The grief is horrible when going through it..mourning the end of a relationship is horrendous, and unless someone's been through it they dont understand. But most posters here, have...so I hope you can take inspiration from the helpful advice theyre giving you. Women are pretty good at helping each other out when it comes to these things, and thank god for it 
When I got rid of my narcissistic emotionally abusive sociopath, some of the things I did (& Im not suggesting I 'know it all', just what got me through eventually)
CBT /hypnotherapy
Took up brazilian dance (had to pluck up the courage, but well worth it)
Forced myself to go to an exercise class once a week - even though I felt I was walking through mud, at first
Read a lot - fiction, mainly, as I found it therapeutic to get into a really good story, and it was really helpful when I was home alone
Spoke with friends, just 2 - 1 who'd been through similar, the other I didnt feel able to tell, but I like talking to her as she's upbeat.
Put my DM on the backburner for a while, and told not to talk abut ExH at all, as it made me feel like shit & was pointless. Still spoke on phone, but without her in my face and the stipulation that my ExH was completely off topic, I could cope. If I ever felt she was straying even near to the topic I just shut her down, and got off the phone.
The thing is, sitting at home with thoughts going around in my head wasnt doing me any good and I knew if I didnt get up and out, then I wouldnt recover. That was a realisation I came to myself, eventually. I felt severely traumatised, to an unbearable point; walking around looking to all intents and purposes ok, but broken inside, with nobody else quite able to understand.
I couldnt let this man be more important than my own physical and emotional wellbeing, not least because when we did speak it became quite apparent to me behind his so called 'Im so sorry oh this is so hard for me too..what have I done..how could I have hurt you this way...blah blah...' he actually wasnt suffering as much as I was at all. Id just been convincing myself that he was. So, I decided to fight back in my own way and not let him and his actions blight my life and reduce me to a shell of my former self. I owed my children, and myself, far more than that. I reminded myself I was alive and well before I met him.
I really hope you find your way to feeling better sooner rather than later. Ive just listed my ways of coping in case any of it is something you feel you could try, when you feel able. Keep going. You'll get through this eventually. Look after yourself, heal, stay positive when you can and as much as possible, dont let negative people within 10 feet of you.