Additionally, the part about relationships goes further than simple nihilism. Plenty of relationships are real and go further than transactions. Not all of them, but many of them. Again, I don't know who hurt you to make you take such a perspective, but your perspective is deeply skewed.
I know it is semantics but it's important. You say "it's not cynicism", "it's just the truth". Cynicism is the belief that everyone is almost entirely self-interested. It squeezes out the possibility of altruism and generosity. Its sort of irrelevant whether it's the truth. So you are cynical.
Love that you've found some joy out of being at peace with your worldview.
The person who thinks they see the truth are the least likely to be the truth seers.