help?

Lilly
Do you just ever feel something at a very young age and then as you progress through out life you finally realized what that feeling was, or more or less putting a name to it?  For me, I've always been suicidal.
I don't know how to describe it. I feel just the overwhelming constant heavy feeling, someone has just sat on top of my chest and putting more and more pressure as time goes on. And the feeling just washes over you, through your whole body,  consuming you and wrapping it's grip tighter and tighter the more you try to fight, it just keeps Pulling you deeper down-like  quicksand, you fight at first because you're scared but after a while you become comfortable. It's all you know, it's all you will ever know after a while. 
For moths on end, years even, just Countless times have I contiplated, tried to kill myself. But in the end I could never do it. I always say i want to kill myself-laughing as if it was a joke but holding off because i have parents (a dad mainly who seems to care)who need me.  A little 12 year old brother needing me more than ever (even though I have older brothers who are in their twenties ) because my parents are going through a VERYYY Nasty divorce because my mom has paranoid schizophrenia and it is just ripping our family apart because she can't see how sick she is. She ALWAYS has been a huge negative part in my life.
 I know this will sound horrible, because she is the woman who gave me life. But honestly if she left or  ended up dying anytime soon. I would be okay with it. I love her but at this point what ever good feelings I've had for her is just crushed.  But As much hatred and built up anger I have towards her I can't just leave my dad and brothers to face it alone.
  
 I also have a best friend who I have at first bonded over our mental illnesses and grew into something more. It's a wonderful but at the same time a toxic relationship because we are both being held together by a little string and what ever love we have left In us,because if one of us goes then the other will just fall apart soon after
She has helped me-saved me so many times over and over again. And if it wasn't for her I wouldn't be here.
She helped me to open up and let someone else in. But even so, I still think of suicide. Constantly. 
What makes it even harder and hurt so much more is I have the most loving and caring boyfriend ever.  He is just so sweet and intelligent, so goofy and just has the most wonderful personality. And with him Even just for a second,when i'm with him the thought of suicide doesn't cross my mind for once. It's heavenly, it's manageable.
He is trying so hard to help me. He is just so desperately trying to pull me out of this hole that I am in and it just breaks my heart. It breaks my heart because for once I have imagined living out a life with him, building a future with eachother when I have never before imagined living out a life. I have goals and dreams but at the same time they have never been enough no matter how hard I've worked for them.
I'm happy with him. I am so in love with him.But at the same time still suicidal. I Sometimes I wish I never made these connections and built relationships with people because I feel so guilty for being this way. If I killed myself.
 how would it effect them? I don't want to be the cause for someone else's life to fall apart as well.
I don't want him to ever feel bad or feel like he was never enough for me. 
Sometimes I feel like I'm being selfish being with him. Because here I am thinking about killing myself when he deserves so much better Because GOD DAMN..He is an amazing person. 
Instead of being with me there is someone else out there who could make him happier. Who has their life together....and it kills me because he fell in love with ME. Every day he tells me. He checks up on me. He genuinely cares for my well being he Makes sure I'm eating, sleeping. just taking care of myself. He is so devoted.
But her I am. Still suicidal.. 
But don't worry like i said before. I won't do it. There is people who depend on me. People who need me.
And idk maybe..HOPEFULLY I will get better.