I need some advice

I'm going to make this as short as possible because nobody wants to read a textbook. I am the usual person whose father left and had a very dysfunctional family, with my mother being an alcoholic and completely emotionally and physically abusive to me and my grandmother for years (I have tried to run away three times and got CPS involved in the past). I was very isolated at school and had no social skills or confidence due to my family environment and since the school was in a small town with kids who were not doing so well in learning whereas I was advanced in some subjects made me out to be a target for physical bullying. I've basically had nobody. For the past four years I made some friends through video games and such, and even though I had my fair share of bad relationship experiences I believe I have finally met the right girl for me. She came from an abusive relationship herself, she's fiercely loyal, and I love her to death. I'd marry her, no question about it. Before her I used to be very suicidal and depressed to the point where getting out of bed was a no-go and every minor thing led to strong urges for self harm. I am still depressed though, not as bad as before but I still sometimes find myself feeling useless or not good enough. My mother has converted to radical religion and has made it clear how much more important it is to her than me, so when I'm not out with my girlfriend and at home I feel the same "I don't belong here" feeling I had at school. On top of that, I think anyone would be hurt knowing their mother really doesn't care for or love them. This woman literally encouraged me to kill myself at one point when I tried to reach out. I've done my best to please her every desire and I'm not uppity or confrontation with her because I am scared. It does not help that she wants full control over me and seeing me starting to have confidence because of my girlfriend and the fact I have plans to leave her she is starting to dislike my girlfriend and I can already tell this is going to go down the path of her trying to intervene in her favor. I know because I heard her talking about it when she thought I was out of hearing range. I am 17, and I have to rely on her for at least a few more months before I would have any hope of moving out with my girlfriend -which means she has plenty of time to basically try and ###$ this up for me however possible. I know I have friends, but I have gone through most of my entire life completely alone. The girl I love is the first one that has actually made me want to live, if I hadn't met her all those years ago even when we were just friends I don't think I would be here typing this. My past abuse has made it hard to feel emotion for anything, but what I feel for her is very strong.
This does not completely remove the depression I am currently feeling. There are days I wake up and realize this is all happening and I just want to die. There are days I think back to all the time people have hurt me and used me and never thought twice about it that I want to die. There are times my mother waves her dominance, and her hypocrisy around me and my grandmother that we have to tolerate and I want to die (or skin her. Recently I've started to feel very aggressive against her and to be honest I've about had it with this garbage.) Sometimes nothing triggers it and I just want to sit in a corner and cry. My mind still drifts to suicide every now and then, but I'm less likely to consider it as an option like I did years back. My girlfriend was sexually assaulted twice and had a extremely abusive relationship that she was in when we first met. She needs me as much as I need her because when she's with me, she feels alive. My mother already knows all of this and still selfishly seeks to put an end to it if she can. She might not have the balls to directly jump in now, but as time goes by she will. I am never good enough for her no matter how much of myself I give up. TL;DR I am everything she wants me to be (besides a completely robotic slave) and she treats me like the son that has done multiple drugs, crimes, and is in and out of jail in terms of "you're terrible."
And I don't know what to do anymore. If I do, I'm wrong, if I don't, I'm wrong.

I am sorry to read of your past. You are definitely not alone. Also had a very abusive and dysfunctional childhood and adulthood. You are very brave for reaching out. Sending positive energy your way.