I would contact Womens Aid for further help and advice. You are indeed in an abusive relationship with your so called partner so it’s over. Get this adult male out of your lives asap and permanently.
Examine through counselling exactly why you allowed this man into your lives at all, I suppose he was all sweetness and light to start with and any red flags apparent were either not recognised or minimised.
Like practically all abusers he is doing the nice/nasty cycle of abuse which is a continuous one. And what do you do and or say when he starts on your son?. Trying to protect him while you are all
living under the same roof is impossible.
What is the situation re the finances and property?. Whose house is this, if it is his are you named or any mortgage or deeds?. If it’s rented is it a joint tenancy?.
Did your so called partner move into your home when your son was ten?. He’s also had a lot to put up with in his young life and enough is enough. This man who latched onto you wants to rule over both you and your son and your son and he’s still a child. What sort of a job does he expect your son to get at a mere 16 years of age?. He’s an appalling example of a stepfather to him and I see without surprise your man does not like your son at all. Such selfish men often target single mothers to abuse them and in turn their kids.
Drinking to numb your pain will not help you; you need to address what has happened re your mother head on. Your drinking is also playing into this man’s hands as well.
Between you and this man your sons home is not stable nor emotionally safe.
Do contact Cruse re your late mother. It’s not your fault she took her own life, it was no reflection on you as a person.