Heart break over and over again

Last November (November 15, 2016 to be exact) a date I'll never forget I lost the love of my life and my soulmate to her addiction. I found my beautiful princess dead on her coach, heroine overdose. I was and am to this day still destroyed by it. I had been helping her get better even had at one point where she was sober for 6 months and was making a lot of head way but then relapse happened during a stressful time in her mind and she went back harder than before. I had made thousands of promises to help her to get her help to make things better and I promised to save her. It's what she wanted she felt she couldn't do it alone, she said that if I kept my end of the promise she would give it 110%. I failed. 11/15/16 I went to her house to check on her and she was gone. I had made arrangements for her to go to rehab in January when I got insurance. She didn't make it to it. I failed her I broke our promise and I couldn't save her. I've been to therapy since then and been told not to blame myself that it was a'll beyond my control. But I can't help but think of all the what it's. I've had a couple of relationships since then but I'm so depressed and broken it's been with girls only out to use me, and I allowed it to happen to keep me from falling back into severe depression I think of her daily, I can't push myself to change my wallpaper on my phone, delete the text, or put away the pictures. Every day my heart breaks again and again because my princess is gone because I failed...

I'm so sorry. My ex is still alive, but I too used to feel so very guilty and like I failed her in the relationship.
Once you force yourself to navigate out of the relationship fog, you will understand and come to accept the fact that:

You cannot save anyone from themselves or their actions.

My ex dabbled in drugs from time to time - nothing heavy, but she is an alcoholic - high functioning too, you'd never know unless you got to know her well. That, combined with a personality disorder (another trait she hides so well) makes for a very unstable, impulsive behavior that potentially manifests itself according to the degree of beverage intake.
She is a very high functioning woman, excellent job, and can mirror anyone she desires in her life - for males, to make them feel like they have met their soulmate if she can siphon something out of them until she decides she doesn't need it anymore. She was living one life with me, and another when I wasn't around.

Long story short- she wanted me to stay with her after all the bad crap that I did nothing to bring on, yet abandoned me a short time later as if nothing happened. As if the time period had never taken place. I was amazed someone could manipulate and negate events to form a non-linear reality, one that they alone believed. The last time we were together several months later, she acted impulsively without warning, something I had never seen to that degree. We were very lucky not to have been injured, or killed. This from a woman who has a young child and, if not suffering from a personality disorder, should put her child above and beyond anything else in her life. I believe once you bring a child into the world, they are priority number 1. Everything else, relationships, personal life, etc. is nowhere near as important as the child's well-being and safety. I hope my ex has at least come around to this way of thinking.

After this traumatic incident, a few close friends blamed me - and I bought into it. After some therapy and kicking those best friends out of my life for good, I got myself back up and realized - NONE of this was my fault at all. Maybe for staying in the relationship, but any choice or action she met was that of her own volition - I have, nor bear zero guilt anymore.

You need to understand and accept that you did not fail your girlfriend. You are not responsible for any choice or action that she made - even a fatal one. I, as you, tried your best, and that is all you can ever do. People suffering addictions must realize they need help, then get help and care of a professional to help them come to terms with the demons from past traumas that they cannot face, or cope with.

Until then, no one, and I mean NO ONE will ever save them from themselves.

Shawn, I'm so sorry about your loss.
I hope you'll find the strength to be able to find some peace and forgiveness. Take care, please.

She did realize she needed help and I promised to get her that help, but I didn't in time. In my life she was the only thing that made me happy now thinking of her makes me the saddest I've ever been.

I'm sorry for your loss to. I also know about promises. Bear this in mind, though; it wasn't your promise to make.
I'm pretty sure you've heard this old saying before, but there ain't no helping someone who doesn't want to be helped. She asked for help and you gave it, but there are some people that just cannot be saved. She walked head on into her addiction knowing the risk and it wasn't really her right to flee her responsibility of it by asking you to be her lifeline. Since you weren't the one circulating in her blood stream at the time, and since I'm sure you did everything you possibly could to help her, feeling guilty or responsible for HER actions, that were NOT your own, isn't the right way to go, because it doesn't reflect reality.

As bad and cruel as it is, honeysuckle just happens sometimes. Trust me. I'm going to be a 38 year old grandfather because an ahole liked children. honeysuckle JUST happens sometimes and it's **** cruel, bro....
You did everything you could and I KNOW it. It wasn't your fault. Only promise you broke is the one you made to yourself thinking you could. Sometimes we just can't protect those we love no matter how hard we try. We're only human.
Life goes on. She'd still want you to be happy.