Hi Serena, there is another possibility for whats happening with your "two selves", its something thats statistically common in teens with "differences" and its often misdiagnosed as mood disorder or bipolar so its worth you checking it out to see if it fits for you and to rule it out if it doesnt. And this may sound odd, but if you are more physically flexible/bendy than the norm (hypermobile) then its definitely worth you looking into because thats one of the biggest risk factors.
Its a physiological condition called Dysautonomia, or Autonomic Instability, and its a failure of the automatic nervous system, (which controls things from heartrate to digestion to emotional stability) to regulate and stay balanced in response to everyday life stimuli. Instead it over responds and over corrects repeatedly like a seesaw, which is chaotic for the body and brain chemistry/hormones etc, and intense suicidal feelings and rage/violence feelings are pretty common when its unmanaged, as is the opposite happy mania stuff. Sounds like bipolar but the different root cause means bipolar medications dont work and so undiagnosed people struggle unnecessarily and get labelled unhelpfully until that root cause is recognised. Which it often isnt by the psych/counselling profession because, being a physical thing, its not something theyre taught about in their training.
Your "mild" suicidal feelings sound pretty normal and appropriate for whats going on in your life and most NT's your age would have similar feelings in your circumstances, so its possible that the tip into the intense stuff is happening when those unsupported emotions get overwhelming. But its also possible its this physical thing that can be treated and managed without prescription drugs and their sometimes unhelpful side effects. And as a teenager who is still physically and neurologically developing, safe alternatives to medication are a good idea where possible.
I'm new here and cant remember what I read about whether external links are allowed, so I wont put a live one just in case. But theres a good series of slides from an experts powerpoint presentation that explain this "dysautonomia-that-looks-like-bipolar" at (http://) ehlersdanlosinfo (dot) wordpress (dot) com/specifics/pseudo-psychiatric-symptoms-in-edspresentation-slides/ This presentation talks about it as part of a genetic disorder but it can also be an issue in people without that disorder as well, especially during puberty.
If it doesnt fit for you then just ignore this but I'm flagging it up as an alternative possibility in case its relevant.
Do you have tools besides video games to use for coping when those intense suicidal/dangerous feelings flood you? Sometimes the sense of (and the reality of) being powerless can increase those feelings so things that help you to feel grounded,and that focus your justifiable anger and grief into inner strength, can increase your sense of personal power and decrease those scary and unsafe feelings. Unfortunately my inconveniently unhelpful mind cant find the words for a single example of what I mean there at the mo but I'll (try to remember to) post again when I can unstick my brain.
Stay safe and use your obvious intellect to remind yourself that its your now situation that you want/need to be over, not your actual life itself. The experience of life is difficult, painful, unfair and overwhelming at times, but its also awesome, enjoyable and enriching. So stick around for those good bits ok.