Perhaps it is time to let the mind go. To let the thoughts go. Your existence is not (solely) your thoughts, you exist outside of these thoughts. The feeling of breathing, the sentiment you experience when looking at the the sunrise, the emotion of sadness & despair or joy & happiness, they are the true essence of who you are. Many over the course of history have believed that our thoughts define who we are. But more likely it is that we feel first and then our mind tries to rationalize it. I love this person and so I find rational reasons to explain why, not the opposite as in I found the right person to love based on some rational criteria so I love them. The mind is just trying to make sense of everything that it "feels" as it tries to make sense of "reality". The true reality is that your dark sentiments are what they are. Instead of trying to rationalize them which, in the end, even if you succeeded, would give you what? Nothing of substance that would modify these said sentiments. That is, unless these sentiments are due to some very pragmatic issue, but this doesn't seem to be the case here. Rather, instead of trying to make sense of your dark sentiments, you can try to just accept them with equanimity.
Bottom line, trying to "understand" the world is the true insanity, not the world itself. The world itself is what it is. This is not to be taken with cynicism as in "it is what it is, oh well..." but more as in "how peaceful it is to be able to accept that I can just dismiss the meanderings of the mind"
Not sure if this helps at all. Sorry if this confuses you more than anything.
