Generally, self destructive tendencies take root in either fear/escapism (such as with addictions), or otherwise serve a purpose.
For instance, self harm often serves as a way to externalise internal pain so that it is seen by others.
If we find the root cause of these impulse to self-harm, we may find a safer alternative, a way to treat the root of the issue.
I, similarly to you, couldn’t love a girl that was very much in love with me, and did her best to stay with me and love me as much as she could.
Now she’s in a psychiatric hospital with no place other than the medical apartment they’ll find for her. Since she was on the streets before she got with me.
It was a hard decision for me, and doubtlessly it was difficult for you as well.
I decided in the end that it was more honest to tell her I didn’t love her than to let her believe otherwise, than to let her believe in illusion.
I felt that continuing to play the part of the lover setting her up for disappointment down the road when I inevitably leave her after coming to resent her, and setting myself up for misery trying to love someone I see more as a friend with benefits than an actual partner.
I am certain that you also had reasons to break up with her. Maybe similar ones?
In your case, I am certain that you thought a lot about it and therefore know that it is the best for both parties long term, even if difficult short term.
I also felt like shit when finding gifts and love and thanking letters she prepared for me, after I left her.
But I know that I did my best so we could have fun and good times, I did my best to help her get better than she was before, and although I couldn’t help her reach all the goals, I was a step on her path, I accompanied her for a while and set her in the right direction with a better emotional and mental foundation than she had before, and even a better material base.
Although I couldn’t help her to find a job, or an apartment, or even convince her to ask for welfare, thus breaking up with her having no place to live and no money in the bank, in the end sending her to the psychiatric hospital got her medicated and being help with getting welfare and a place to live while she get on her feet.
Doubtlessly, your circumstances certainly differ, but the fact remains, that it would have been terrible for the both of you to continue in a loveless relationship.
I told her saying that I am very sorry I couldn’t love you anymore, she told me she felt it, and said sorry and that she did her best but couldn’t get me to love her.
It’s just a sad thing isn’t it?
But I really feel that there was no other choice than to be honest with her, both for her dignity and joy or mine, although it hurts us both.
Idk what would be the best subliminal, but I know for sure that forgiving yourself, and thanking yourself, for what you did helps.
And that forgiving her and thanking her for what she did helps.
I am certain you both did your best during the relationship, until the end.
And we can’t ever do more than our best, can we?
And if she’s only even slightly better than she was before, if you bought her good times and good memories, than you can be proud of yourself.
And if you’re even slightly better than you were before and if she bought you good times and good memories, she can be proud of herself.
I wish you to find the happiness and good that this separation brings for the both of you, the wealth of opportunities that arise from not clinging to what’s gone by and to what is no longer.
Peace 
