It's 2am and I can't sleep (rant/seeking advice)

I had no idea what to put as the title, also please excuse the grammar and some spelling I'm using the app on my phone so I won't be going through it.Anyway as the title says, it's 2am and I can't stop thinking about what happened a few hours ago and what my sister said to me. Brace yourselves you're in for a D and M lol.I was raised by a Jehovah's Witness not a mother, at least that's how I look at it. My sister had a fight with my mum yesterday evening so I invited her around for dinner with my niece. My sister got to telling me what they were fighting about my mother not telling us about an aneurysm she's had for a while, my sister got angry because my mother could drop dead at any moment and we'd not have a clue why. Shortly after they strayed down to arguing about me.My sister started arguing about how I'm gay because according to my mother I choose to be, however before she was a Jehovah's Witness she had many gay friends, according to multiple friends she no longer talks to, not out of an argument just stopped talking or making contact.I've never been able to have any form of positive relationship with my mother at all, since she kicked me out when I was 16 I've barely made contact with her, I only see her when I'm with my sister. As I've gotten older (now 25) I've come to realise I'm not angry at my mother I'm angry at the Jehovah's Witness that's taken control, my sister managed to get my real mother to show one evening when she pointed out flaws in her religion, my mum broke down and finally told us that she needed the religion because if she didn't have the religion she didn't have anything left. When my sister told me this ages ago I literally stopped and said to myself "mum" because it was my real mother talking not this Jehovah's Witness, for the first time in my life I got to hear something real a true about my mother it's hard to explain but I felt in a way I got to visualise my real mum, the mum both of us lacked as children, my sister raised me from the age of 7 when my mother would just leave the house, leaving my sister to care for me.My sister was arguing with her about me not having a family and that she was my only family. She's right, I don't have any other family but my sister, my other realities are nothing but useless tools in the shed, my cousin and Aunty only spoke to me because they had a bet running I was gay, no joke when my cousin was working as a manager of a phone store near home my sister and I stopped in to say hi while she was on her break and I wanted to tell her I was gay, I was actually excited about it for once I could be me I recall her words "really? Ha! Mum and I had a bet going you were gay" since that day, not a peep from either of them, they only spoke to us at once every 5 year family events or funerals, when my nan was alive she was the only reason we all spoke to each other, now there's barely a hello, we don't get invited to Christmas or Birthdays we're the outcasts to them.I'm getting off track. My sister was right I have no other family, I considered a woman around the corner I knew for 15 years my mother because she looked after us better than my own mother and she could barely afford stuff for her own son let alone us, turns out I was just being used, that day was a right punch in the stomach.I wanted to go to my mums last night and say everything that's been bottled up but if I do my sister will likely get kicked out and I wouldn't want that hanging over my head. I want to tell that Jehovah's Witness everything I think of that fucking religion and then some, but I also want to tell my mum it's okay and that she doesn't need to feel alone anymore and although I don't show it, I love her dearly. I want to tell mum that it's okay. She became a Witness when she was pregnant with me she was suffering from depression because of my father leaving her, that religion hooked its claws into someone that was in a vulnerable state, that's exactly what I want to tell my mum. I want to tell her that she's not alone and she has us kids 24/7 but I know all I'll get is "Jehovah doesn't want that for me"I don't even know how to approach her, I want to do this for me so I can get rid of this anger towards the Witness I've had all my life. I really shouldn't appear to be complaining, there are people way worse off than me who would trade places in a heartbeat but I need some advice on how to do that and I don't know where else to look.